If you read the guidelines, there’s quite a bit about being polite and not inciting flame wars, not only off topic items. It regularly happens that posts or even users get removed for that reason.
There are platforms that have much less strict standards with regards to that - yet you consider this the more agreeable platform. Maybe the reason is that it’s actually nicer to have a conversation in a place where you don’t need to deal with an asshole that starts yelling and insulting everyone at the table.
Think about this in real life: would you want to frequent a place where the loudest asshole gets to insult everyone present or would you rather go to a bar where at some point the Barkeeper steps in and sorts things out?
You're speaking of some idealized moderation system where tone and politeness is enforced, and human corruptibility does not entice moderators into censoring speech they disagree with? Yeah sure, I'd love to be there. It's just a rare thing to find on the modern web, and it's not guaranteed to last for any length of time.
The modern web example of your bar scenario is more like this: the bartender doesn't want to hear [opposing political/societal issue opinion] at the bar and starts kicking out everyone he disagrees with. The kicked out people go start their own bar. Now there's two neighboring bars, MAGABar and LibBar; customers are automatically filtered into attending either bar by an algorithm. If you say anything that the bartender disagrees with, you're permanently banned. The fun part is that you can be permanently banned from BOTH bars if your viewpoints don't fall in line 100% with what the bartender wants to hear.
Oh and you can't go to TechBar anymore either, the bartender heard you said something critical of furries at another bar, so now you're banned and not allowed to talk about computers.
There are platforms that have much less strict standards with regards to that - yet you consider this the more agreeable platform. Maybe the reason is that it’s actually nicer to have a conversation in a place where you don’t need to deal with an asshole that starts yelling and insulting everyone at the table.
Think about this in real life: would you want to frequent a place where the loudest asshole gets to insult everyone present or would you rather go to a bar where at some point the Barkeeper steps in and sorts things out?