I'd propose letting threads be tagged [NSFW] if they're gonna be a heavy or mature topic. I believe these threads can coexist, and trolling/derailing that may occur can be dealt with in the same manner as any other thread, and period.
I kind of like this idea, though I wouldn't go so far as to say NSFW. Maybe being tagged as [Mature] might be better and maybe keep a close eye on those threads? That would at least give a distinction.
My thought is kind of that age-restricted forums are usually horrendous and devolve into creepy disgusting ♥♥♥♥ more often than not, no matter what the rest of the community looks like. So the compromise for not having one of those in a community with a significant 16+ population is kind of to be more free in the general chat areas. I realize that many people advocate that PC should be open to ~adult~ discussions. I've seen people of the opinion that PC shouldn't enforce traditional content-appropriateness views upon the community. But we do have to draw a line somewhere, do we not? And the line should be pretty solid across the forum as a whole. Because if it isn't, it brings up a whole slew of subjectivity with no rules to back up a staff member's decisions. Then there's outcries of how unfair and horrible staff is, and favouritism to staff that are more lenient, and that whole divide. And the people crying "unfair" wouldn't be wrong, technically. And that just causes so many problems.
I've always kind of seen PC as like, 16-and-under content. I don't mind educational sexual discussion when it comes up, because that's kind of a thing that more people need? But when stuff starts getting personal, it weirds me out. When discussions come round about violence and that it freaks me out. Mainly I just avoid it, but I've seen a lot of things lately that are just gross. That I just see coming up kind of out of nowhere. idk. I think everyone at this point has agreed that D&D is a place for 'mature' topics and people who don't like it stay out. But General Chat has never been a mature place really. The relaxation ideas are kind of causing a relaxation of the content rules I think. And it's mixing things I'm kind of uncomfortable with in with the stuff I'd like to participate in. So maybe creating a tag for the mature discussions would at least help create a divide? Maybe things tagged with mature or whatever could have a general rating of 16+, while other things should really just keep to PC's usual PG-13 limitations? And just have that be a thing people know.
Alternatively, pop another subforum in for "Mature Chat" that's not age-restricted but keeps all the topics that get uncomfortable for a lot of people in one place. I really do think PC should in general be a PG-13 environment.