People definitely off-class more than they should because they can abuse bugs to avoid getting auto reported or they just don't care because the cooldown for offclassing is only like 30 minutes or something. the issue is that the automatic cooldown for offclassing is too short for it to be an effective deterrent, but at the same time it's hard to justify making it longer when it bugs out sometimes and bans people for offclassing in pregame.
Bear’s strictly no offclassing lobbies is an interesting idea. My one concern is that Tf2center is a lot of pubbers' first exposure to competitive tf2 and the optics of having the most accessible platform just outright banning offclassing is not good and would fuel a bunch of false narratives about competitive tf2. I'm not entirely opposed to literal no offclassing being offered as a 3rd option though. Its actually kinda cool because then tf2center becomes somewhere between soap DM and a pug. However, we should keep in mind that you don’t need to offclass to troll, so realistically I think what will happen is that people who like to go pyro to mid will instead opt for playing trolldier and demoknight. I think the best way to mitigate trolling is to make it easier to report players by lowering the number of votes required to get a sub when that player is offclassing. Just lowering it from 4 to 3 sounds silly but I think it would make a big difference and I like it because people do have fun in goofy 1am tf2center games. Sometimes offclassing is fun and fits the vibe, and other times it does not, and that's why I’d like to make it just a little easier for the players in the game to get a sub if they think it is necessary.