Why do people instantly draw parallels to their own backyards when talking about this? The riding community in Moab is a lot different than the one in Squamish.
There are lots of places mtb's shouldn't go as well. Hikers too. May as well include hoseback riders and unicyclists.
If your area can support multi use then it makes sense to keep it open for all. If motorized bikes are being used in questionable areas then they probably shouldn't be there in the first place. I knew that when I used to ride a dirtbike, that I should stay off mtb trails and trails that would see foot traffic. Even on my mtb, if I am on a trail that sees a lot of hikers, it probably won't be as fun constantly having to check my speed, so I avoid those trails. Mountain bikes on moto trails doesn't make a lot of sense either, mostly because of the chance of getting run down.
Since we are drawing parallels, I am sure glad I don't see ebikes on our local trails. :nono:
Its not necessarily about who originally used the trails but what the trails have become. It would be very awkward seeing a bunch of dirtbikers on Fromme every day now wouldn't it?