MTB's have been equipped w/Fox Floats since the early 2000''s and the rebuild kits are like $15 and take an hour to install w/ no special tools. The only possible area of concern might be worn pivot points, but they have been using sealed brg.s since 2002 and they will never get worn street riding. Besides, it's as easy to find an older low-time full suspension mountain bike as it is to find a little used hardtail. People buy MTB's, realize quickly that trail riding is a lot of work and park them.Whether they are hard-tails or FS hasn't nothing to with that.There certainly more mint used mountain bikes out there than DJ's.I am absolutely convinced that a properly functioning hardtail can be counted on whereas who knows about a 15+ year old used FS bike.
MTB equipment is not meant to be cornered on pavement at 20+ mph, my previous ride's fork shuddered and buckled under side loads present due to the grip and speed that pavement + electric provides.
Oh, I suppose motorcycles w/ suspension are hazzardous and the manufacturers should go back to the hardtail designs of the '40's. The cornering limits of bicycles, like motorcycles are mostly a function of the tires. Besides, not many riders here think they are Valentino Rossi. That statement is just pure nonsense.
Since you apparently haven 't noticed, mountain bike suspensions have this amazing feature, it's called adjustability. That somehow a hard-tail will provide a better ride than a suspended bike at speed just defies logic. Even suspensions 10 or 15 years old work perfectly on the street. The quality of travel hasn't changed that much, it's more about the amount of travel. 3 or 4 inches is fine for the street.Lost in all this is that MTB suspensions are not made to provide a smooth ride on pavement at high speeds plus older, used MTBs are primitive by today's standards and their shocks will be old, poor and possibly worn as will their pivots.
Try an understand that not every rider here uses his or her ebike like you do and to make these "etched in stone" statements of what works and what does not serves no purpose to anyone