I don't think usability problems in Lemmy are related to the protocol. For me open source alternatives carry the promise that they will only get better, while profit-oriented alternatives will eventually have to get worse.
I don't think any of what makes Lemmy difficult to use is a necessity based on its distributed nature; its a result of the developers being more geared towards the back-end than towards the front-end. Which is not an inherent weakness - the back-end needs to be good before a nice front-end can make sense. So I'm optimistic. :)