Probably the best, deepest LGBT+ issues discussions I've ever had have been on their /lgbt/ board. They were filled with people yelling obscenities too, but that doesn't bother me. I guess it's the culture I grew up with, it's natural to engage in discussion while people are yelling around me.
I'm really glad there's still a place out there that believes in free speech as a foundational principle not to be infringed upon except as an absolute last resort. I'm glad not everywhere is 4chan, but 4chan is a gem of discourse in today's world if you ignore like 90% of it. I'm increasingly convinced that that 90% is the inevitable cost of the wonderful 10% that represents the sharing of intelligent thought without fear of reprisal.
high IQ post. that seems to be a pattern in many facets of life. (raising children, starting companies, dieting, traveling)
The Wikipedia page[1] claims that “Registration is not possible”. Is it wrong, or am I misunderstanding?
There is also the concept of a tripcode, which is basically an HMAC with a key that the server has a user provided code that is shown next to your post. You can use this to prove knowledge of the code. Usage depends a lot on which board you're on, but is generally frowned upon.
Some boards (such as the infamous /pol/) also have IDs on posts (IIRC derived from your IP address and the thread id), so that posts by the same user in the same thread can be correlated.
Other than that, everything is anonymous.
[1] minor exception is the "since4pass" option which just adds a little icon to your post indicating how long you've had your pass. This is basically never used (perhaps because even 4chan posters don't want to advertise that they're paying for 4chan)
A site could still allow accounts and banning and have guidelines around discussion topics, it doesn't have to be completely anonymous like 4chan.