We certainly do create our own filters by what we subscribe to, how we moderate posts, or how we otherwise personalize our accounts.

There's an argument that people should self-police their own filtering to allow diversity to flourish, but these self-created filters aren't the issue, in my view.

The worry is when self-policing isn't an option, either because people aren't aware filtering is going on in the first place, or that they don't have any control over the filters.