Well the simple reason is you can get stuck in certain world views or ideas which are wrong and hurt others.

In most cases you're fine, like talking about your favourite TV shows or whatever. But it's also easy to get stuck in a view like visiting your country's instance and it turns out it's a bit radicalised against immigrants, or certain places where you end up blaming everything on women and the "woke movement".

In a lesser way it can get you stuck in toxic ideas (e.g., PC/Playstation/Windows/Xbox/Linux is better than the other one and you are dumb if you disagree!).

Just depends on the community at end of day, but the more echoey chamber it is, the more likely you'll end up with those sorts of us VS them world views that are a bit blind and horribly biased.