Yes. I can only speak for Italy and Slovenia, and, while it's true that every niche counts and everyone chooses their own battle, it does seem a bit preposterous to blame MTBing for environmental destruction. Downhill riding, if you climb with vans or lifts - yes, that makes sense; but those who only use their own legs play a really marginal role. Yes, they might contribute to erosion, especially in the most popular areas (so maybe it makes sense to have separate trails for hiking and for biking), but aside from that it seems to me that MTB is actually one of the lowest-impact "action sports", not least because it's really easy to find suitable conditions, so there is no need to travel very far (unlike, say, surfing). It also doesn't involve more infrastructure, at least not in my neck of the woods (ha!), as forest roads are almost ubiquitous - for farmers, loggers and forest guards -, and they serve bikers just fine.