It very much was not like that, even in the 90s when Green Day and the Offspring blew up
Even when Blink 182 became the "next big thing" it wasn't like that
Yes, there were always elements of "that's not punk" - policing, politicking, and gatekeeping, but that wasn't what made punk jump the shark
Punk died in the 2010s when it was converged fully by the intersectional elements of the neo-marxist left - punk was always left wing, so it made easy prey for the types of tactics that the corporate HR uber-Karens use when they want to wear something as a skin suit.
Ironic, because punk used to be one of the best vehicles for left wing politics and ideas, and by embracing a very specific flavor of them, instead, it's a complete fucking joke now
I've played in punk bands forever and you guys would laugh so hard if you heard some of the shit I hear at shows.
Every single band (and i'm not exaggerating, every single one) has to stop in the middle of their set for the "virtue signal monologue" as we call it. You have to stop in the middle of the set and say how bad you think racism, sexism, homophobia, transphobia, etc etc are - and if you don't, you're going to get the side-eye from the crowd and other bands. It's absolute insanity. Every band does it because every band is terrified of being cancelled or catching an untrue me-too allegation. It's like 1984 with mohawks.