whether you agree or not, asking "what's the issue" misses the point very badly, since the article is almost entirely about what the issue is (i.e. that most people will not change defaults and the default is to centralise on the bluesky servers)
It's weird to focus on that when there isn't a single thing in software that doesn't suffer from "everyone will just use the default anyway"
The fact that the system is built around this escape hatch makes it miles better than almost all other social networks. An escape hatch doesn't need to be used by most people to be valuable.