A very similar experience here. Reading comment threads over the years has absolutely turned me on to perspectives I never even conceived of previously. I've reconsidered my positions (on political and technical matters, mainly) by reading the discourse in comment threads.

Sometimes I post to clarify my own position. Writing helps with that.

There's a whole field of street epistemology which is about persuading people. Arguing with them is one of the least effective ways to do that. Socratic dialogue sometimes works, although for any belief that has an emotional root you're likely to hit a crash out point.

It turns out the most effective techniques are manipulative. The best persuasion doesn't look like argument or persuasion, it looks like something self-evident you can't help agree with.