the former's status as an Obviously Federated Platform that Works Differently in all the ways it does has a hidden drawback, besides the hassles one can experience in using it. a friend pointed out "an absence of non-technical users"
people who use mastodon are often there because they are interested or invested, technically or ideologically, in the structure of the site. lots of times folks don't go to mastodon because they want to talk to their friends, they go there because the structure of the system is interesting
mastodon has hurdles. it has all kinds of hacked together shit you have to understand to use it. trying to reply to a user on another instance is weird as hell.
twitter and cohost have made it easy; you don't have to understand how the site works to use it. this lets people who aren't interested in or can't understand the technical side post as they please without having to understand what it means that their own or their friend's instance has "defederated" or what activitypub is
artists and musicians and ordinary people who are only interested in their work or friends, not in how the system underneath the website works, can post without worry. it leads to a much better diversity of users in many fashions