There's a Kurzgesagt video that talks about how it's not so much that the internet is forming echo chambers as it is encouraging arguments. People aren't just finding others that they agree with, they're attacking people they don't.

Finding people who agree with you isn't necessarily a bad thing. Attacking everyone who don't because you now know a bunch of people have your back is the dangerous part. Algorithms play this up because it drives engagement. Two tribes arguing keeps people coming back for more, so it ends up being all you see online.