I understand those concerns, but I’m not sure if this really improved the security of mastodon, an inherently very insecure software, and it definitely deprived us of a useful tool. Defederation works at stopping spam, but I don’t think it really helps much when it comes to preventing people from seeing things you post. It stops a single server, but bad actors can just migrate to a new one, or spin up a new hostname.
I use FBReader everyday. When you say that it’s netblocked, what do you mean? I’ve been able to use it in airplane mode with no issues. I’m using v3.7.6.