On a forum of this size, in order to return to the level of quality we had in 2011, you'd basically have to turn the forum into a police state. And even if you were OK with that in principle (which I'm not...), it'd push away many of the good contributors. Often it seems like a situation of "size, freedom, or quality: pick two".
You wouldn't. I think if you removed signatures completely that would solve the issue instantly. All those who are causing the issue in the first place would just leave and to never return. Problem solved. This forum would probably go back to how it was in the good old days practically overnight. I think if you even just required a high amount of activity to get a signature that would solve a lot of the shitposting. I don't think having some minimum standards on how signature campaign managers can operate here would turn the forum into a police state either. Most campaigns would clean up their act when they realise there's some punishments for how they behave here. It's because they can get away with doing nothing that they do. If we stopped removing ref links then people would continue to spam them all day everyday but removing ref links doesn't = police state. There's rules here to try keep some order and not ruin the experience for everyone else. Signature campaigns have practically destroyed the forum and the vast majority of people don't think that's ok and simply telling campaigns to clean their act up or they can't advertise here should be common sense and not some form or tyranny.
There is room for improvement, though, and there are probably many ways of incrementally improving signal-to-noise without sacrificing much or any freedom.
I agree there's lots of things we can do but when can we try them? The longer we leave things the worse things get and more genuine users are pushed away and leave only to be replaced by dozens of spammers in their wake.