> Why does my browser need connectivity to some internal services? I am fine with offering opt-in service integration (Firefox Sync, Pocket, ...) but is there a reason why Firefox needs internal infrastructure to do the one thing it is supposed to do, browsing the web?

If you read the whole post, the connection was explicitly for telemetry (and so you could avoid the issue by turning off telemetry), and it blocked other connections because the request went into an infinite loop rather than failing outright.