Smaller people and people who are just getting into the sport are not exceptional cases. Heck I wouldn’t call my own FTP “exceptionally low” – intervals.icu puts me smack in the middle of the bell curve for my age and gender – but 100g of the mix I use would be roughly what I burn during my favorite Z2 session, or this family of Tempo sessions.
Optimal fueling doesn’t mean “fuel until your gut complains”, it means “fuel until there’s no longer a performance or recovery benefit”. If I can get the same benefit out of 60g/hour that I’d get out of 90g+ then I’ll save myself the cash, heh.