People may not need "validation", but to use motorized means on infrastructure meant for non-motorized use, they do need authorization. MUPs were indeed designed, built and intended for use by different types of users. And yes, as mentioned, a lot of fast bicyclists fail to realize that. But MUPs are intended for multiple NON-motorized use. People who have a NEED to use a motorized assist have the means to be authorized to use their motorized assist on MUPs, just as motorized wheelchair users are authorized to use their devices on sidewalks, MUPs, etc.

This goes beyond e-bikes, of course. There's been a huge uptick in the presence of various stand-on motorized devices on the MUPs here - motorized kick scooters, those one-big-wheel "skate"boards, etc. Obviously these do not fulfill any physical need for mobility assistance. And since they do not qualify as vehicles (seat, at least two wheels at least 16" or more in diameter, at least one brake, etc.), they're "motorized toys", and have no place in the public right-of-way.

It's easy to forget, with the expanding multi-use infrastructure we have today as the next "roaring '20s" approach, that bicyclists fought hard not only for the infrastructure we have now, but for fair use of it, and fair share use of public right-of-way in general. This included working hard with state legislatures to draft specific definitions that describe how we use the infrastructure we have now. Watering down those definitions just for those who WANT some newfangled assistance (those who NEED it excluded) is a disrespect for those who fought for what we have and enjoy now.