Everyone has forgotten it ten minutes later. That time you partied with a punk band is a memory that sticks with you. It's not all about reach, it's about connection.
If there's depth to your work, and you're true to the ideals you espouse, then people will respect you and connect with that. Maybe on a smaller scale, but to a greater degree, and for longer.
Measure it? It's entirely subjective and therefore isn't compatible with measurement, obviously.
I think the vast majority of shitty pop songs fade away.
You should look in the mirror maybe. You're still here, too. Arguing about something that doesn't matter, against a point you don't seem to have understood. I guess we're as bad as each other.