As a user for almost half a decade I can confirm this button has always been there, and I have witnessed multiple private groups getting banned upon reporting

Honestly I get the feeling the problem they're having right now isn't that it was hard to report things to the moderators to action, but rather that telegram is a haven for people who were absolutely there to do unsavory things and were unlikely to report each other.

Perhaps I've misunderstood?

It's a strong tradition in France that when you get pissed off with a company you take its CEO hostage.

It seems to be really effective.