I think there is definite logic to support a training approach that incorporates some longer easier rides, in addition to the usual intense stuff.
I think a polarized model works well for a certain profile of athlete, but not everyone, and some athletes will benefit significantly from adding sweet spot workouts to the mix.
This thread is well worth a read.
Mikael is going to be interviewing Dr Seiler for an upcoming podcast, so that should be very interesting.