I have already conceded that they are both recreations (not
sure how "valid" mountain biking is though), but they have to be managed
differently. Hiking is clearly a superior recreation compared to mountain
biking, but even if it weren't, it would still have to be managed
differently.

Hiking is NOT "clearly a superior recreation". That's a value judgement that many (possibly most) would not share.

All recreations have to be managed sensibly ... but that means pragmatic solutions to individual circumstances ... not messianic proclamations !

YOU posted the video links Ed ! Are you mentally impaired
? Why do you keep posting evidence that refutes your own positions ?

If you really want to see how mountain bikers behave on
trails, go to YouTube where you can see tons and tons of videos showing bikers
****ing up the trails. Trust me on this, you would not want to be on any hiking
trails used by mountain bikers.

Ed, YOU posted these links. Are they not representative of reality now ? If so, why did you post them ?

I think you'll find that, provided you can stop within the
distance that you can see to be clear, that there is no issue whatsoever with
disparate speeds. Why do you care what speed I'm doing elsewhere as long
as I pass you carefully and slowly and don't put you at risk ?

Trails wend and wind and sightlines are sometimes practically
nil.

What bit of "stop within the distance you can see to be clear" was unclear Ed ? If the sightline is practically nil then the speed needs to be that much slower. If it's a long way ahead then speed can be much higher. Simple.

A biker can be on you before he even sees you. The truth of the matter is
that bikers do not like to brake under any circumstances. You need to answer the question of why motorcycles and bikes should not
share the same trails. After all, they both not only have wheels, but have
brakes too!

Oh do stop going in circles ... it's very tiresome. I've addressed this issue ad nauseum. If power, speed, weight, noise and environmental damage differences between powered trail bikes and mountain bikes are not obvious to you then you need glasses and a hearing aid.