Note that Tile already does this mesh network of crowdsourcing. The issue is that Apple pushes privacy so much that it's bound to be a bigger story when they mess up compared to others, as stated in the OP.
It is a bit different if your stalker used Tile to track you. You'd have to download that app and opt in.
Tiles can be marked lost until found by other users with the Tile app.
Unfortunately things start getting weird/potentially negative at scale, but at least Apple is trying to get ahead of the problem.
No it wouldn't. If your phone can track an AirTag being used to stalk you, it can also alert you to this stalking.