There are a whole lot of new riders out there.
Don’t be a dick is the #1 rule.
If I wear roadie (?) Gear on the MTB trails, I’ll get loads of weird looks from all the dudes hanging out at the bottom of the trails.
None of them are welcoming. They watch your Strava run as you hit the bottom. If you’re fast on an XC bike they’ll make a point of smashing your time in full face helmets and armour.
Impressive.
It’s similar to the looks I get with my muddy MTB shoes on the road bike.
In general, the biking community needs to do better if they want more.