[migueldeicaza]

Not really.

The echo chamber is only an issue if you isolate everything. But given the hundreds of thousands of disparate communities, blocking one or two, or even dozens of groups does not amount to much towards creating an echo chamber.

[strictnein]

The blocklists are targeting people in the same communities, but who hold differing views, so it definitely is creating echo chambers. You don't need to isolate everything, just those holding opposing views in your community.