In years of trying it both ways, I see zero difference.
Drying my kit in the dryer on low-heat/delicate immediately after washing doesn’t seem to damage the cloth/chamois despite years of doing so, is better than letting it sit wet for 2.5 days (which is how long it takes the chamois to finally air dry), and is basically just manufacturers being extra cautious so they don’t have to deal with warranty claims from people with dryers that are way way way too hot. You’re supposed to replace bibshorts after a year of use anyway, during which it will certainly live through a couple of delicate drying cycles.
(sidenote: chamois lifetime should be given in number of uses, not time. That kit I’ve had in the plastic for a year is still fine, the kit I wear on the trainer 2x a week is dead. Spoiler alert: they are the same age.)
Really?
Side note I had the most stressful day a year ago when my washing machine became faulty and boiled my cycling gear - I put them on a 30 degree (Celsius) wash but when I opened the door a load of steam came out and the clothes were too hot to touch. Assume the temperature sensor had gone and it just kept heating.
To support the ops hypothesis though the kit on the whole survived - my castelli kit including 2x perfettos lost their labels, chamois got dyed black in some bibs and some under armour base layers are now permanently wrinkled (but they stretch anyway when I wear them anyway.
I thought that it all would have just melted together based in the warnings on the care instructions but kit still in use a year later 
You must live somewhere very damp? We don’t spend a lot of $ heating the house in the winter - I’m wearing a t-shirt, sweater, and vest LOL - and my thermal bibs/chamois hang dry in about 8-12 hours (Pactimo, Voler, Assos). Usually get 2-3 years of bibs that are worn once a week, I wear them until the chamois gets compressed and loses support.
Remember (or take note) that not every country has the same types of clothes dryers plus there’s models that don’t have low temp drying.
We either stick ours on the clothes line in summer or the drying rack next to a radiator in winter, we’re in northern England, and they are typically dry within a few hours to overnight in the case of indoors. (we don’t have a hot house - the thermostat controlling the radiators is set to 16C)
Our problem is the water - we are on a private water supply and it’s somewhat acidic. It gets tested every five years (legal requirement) and it’s more acidic than coffee! It’s not the chamois that goes, it’s the lycra. Let’s just say it can be revealing 
16 degrees 
Try hanging with fan blowing on them. Usually dry in an afternoon even when humid.
30 degree / quick wash / non bio, hang on dryer near radiator or on the line in summer. Whilst I’d never really think about tumble drying the only real condition I have adhered to is not using softener, the quick wash also makes sense.
Really don’t use fabric softener though or your gear will start smelling foul 
I put everything in the dryer, no idea if we have a “delicate” program. I keep bibs for years until they fall apart. At least for indoor riding, outside I have to look fashionable with the newest kit. Makes me feel better. At least +15W by feeling pro.
The reflective logos and vinyl logos take the beating. Everything else is probably fine
I’m actually running an “experiment” right now because I have a problem.
2 pairs of the same bibs that both get used twice weekly, one pair I hang dry, the other I tumble dry. They’re different colors to differentiate them and I’m almost a year in with no noticeable difference other than the yoke of the bib straps-this is slightly frayed on the tumble dry pair and the hang dry pair essentially is almost the same as when they were new.
Chamois feels exactly the same.
I have a hang dry station and it usually takes 12-18hrs for them to air dry.
Same trainer/guest room where I dry my stuff is set at 57. I put stuff in there last night around 9 and took it all down when I got home from the gym an hour ago (8am), all dry.
Tri shorts so thinner chamois but regular bike shorts never take more than a day. So they also don’t really have much to lose, I have one pair that is over 10 years old that I use if I forget to do laundry.
I’ve put them on a rack near our wood stove thinking they needed the heat but didn’t.
We actually got a new washer/dryer last week so that was the second load. Our old dryer was the same temp no matter if you had it on high or just no heat/fluff it was always hot. May test it with some sport stuff soon.
Wait, what?
Me too….I take no special care for my kit and they last years. I usually get bored with them before they wear out.
Summer Kit weather for us northerners
I am doing my laundry at my GF’s apartment complex, I am not risking expensive stuff in those driers
Basically 0% humidity where I live, stuff dries pretty quick.
The only thing i do not do is use softener…
but I do put my wo gear in the dryer… no issues…
Totally panicked when I pulled my husband’s spendy bibs out of the dryer. Didn’t see them when I was moving laundry over. I had just seen someone mention on IG that their shorts (same brand) shrunk at least a full size after going through the dryer.
But luckily, he swears they feel/fit no differently.
I’m in Colorado now and things are dry in just a few hours. That was not the case with my husband’s gear when we lived in SE Texas - and everything smelled terrible, no matter what we did. Smell was probably more of a “wear” indicator than actual wear.
Huh - I use my bibs for years until the seams start to give, they are see through, or I just get tired of them. Machine wash and dry without issues. Buying new bibs is $$$. I started to replace my bibs last year – most of mine were around 10 years old (with a solid 7-8 year riding hiatus in there) but felt fine for the most part.
I do 3-4 rides a week (mostly inside) and typically max out at 2 hours though so maybe less use than others around here.
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Unless you used a very high heat, a single tumble dry is not likely to cause an issue for a quality set of bibs.
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The issue can be repeated use which can lead to premature failure of materials in the bibs. As seen, some people get away with machine dry while others see issues. I smoked a series of kits before recognizing the common recommendation to air dry only.
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Experiences vary greatly for a number of reasons. The “safe” recommendation from manufactures is to avoid machine drying. People that still do it and are happy with the results are great to continue doing so. But some will also find early decline in materials that might be avoided.
Same as OP, with only 2 exceptions over the last 5 years. Both on inexpensive bibs, including the popular/polarizing Black Bibs. In both cases the chamois got bunched/folded inside the spandex layers, with no way to easily reposition them without unstitching.