

Centralization is a weakness. These services can be targeted by governments that want to limit communication. Free speech is a commodity, and servers host this free speech. If a hostile organization, such as a government, targets a channel of free speech such as those hosted on a platform that makes it easy to setup a mastodon instance, this become an easy target that will affect a large portion of users. If you are serious about freedom, you have the freedom to self-host your own platforms.
I would say this is a little too pessimistic. Legislation in the EU and California have both forced tech companies hands, it’s why we can download all our data and delete all our data (supposedly, doubtful in reality) on the large tech platforms. The issue I see is getting legislation that attaches itself to a standard controlled by the W3C. You are right that it won’t be something done by the US federal government though.