Counteranecdote: I remember being on a forum for a good ten years while it had a free speech policy. It worked just fine as in practice social pressures and being shouted down kept any talk of "gas the jews" basically nonexistant.
Unfortunately, the forum moderation team became woke and started introducing rules ouutlawing types of speech they disagreed with. This ended up reinforcing a whole load of vicious cycles (conservatives self-censoring, conservatives being ejected, moderation drifting further left) and you ended up with a very nasty circle-jerk of endless posters trying to one-up eachother with the latest scandal about how Evil their enemies were. Surprisingly, it didn't just kill discussion of left vs right on social issues, it killed basically all discussion of non-culture war political topics as well, drowned out by the purity spiral circlejerk.
Unfortunately, the forum moderation team became woke and started introducing rules ouutlawing types of speech they disagreed with. This ended up reinforcing a whole load of vicious cycles (conservatives self-censoring, conservatives being ejected, moderation drifting further left) and you ended up with a very nasty circle-jerk of endless posters trying to one-up eachother with the latest scandal about how Evil their enemies were. Surprisingly, it didn't just kill discussion of left vs right on social issues, it killed basically all discussion of non-culture war political topics as well, drowned out by the purity spiral circlejerk.