So, good question and one that new members often ask.
The reason, as stated by the 'moderators' some time ago; is to keep down the heat in inter-member flame wars.
This forum is the only one I spend any time on, anymore. Sure, there's a couple more, one cooking and one gardening, plus some religion related ones. But when the moderator is a Father, things stay pretty calm if the poster isn't a troll.
Even Next Door eventually went to hell when product influencers and political misinformation operations found ways into it.
And of course the last point is, "their house, their rules".
I was banned once for good, and when I did get back, I had a completely different mindset about being a member.
Yes, some probably still think I'm a *******, but at least I try.
Bill