What you are describing -- a system where I have to maintain accounts on a number of separate networks that don't interoperate due to content control disagreements -- is an ecosystem of competing centralized systems, not a decentralized one, and that people who run their own servers are reportedly presumed evil and defederated either by default or at the drop of a hat is a visceral demonstration that this setup undermines most of the benefit you think you are getting by calling it "decentralized". The reality is that many of the people using Mastadon would be not just "happy enough" but "actively happier" (per all the clearly ridiculous controversy surrounding people doing the supposedly-evil work of building search engines or, heaven forbid, being able to quote-tweet without permission, lol... if you are going out of your way to prevent hyperlinks, something seriously wrong has happened) using a centralized competitor to Twitter that was merely run by someone they liked.