Personally I think this could be solved by having two types of instances: 1) generic boring ones where you can make your own personal profile 2) specific ones acting like special interest groups where you cannot create a profile but can only post using your already existing personal one from a "generic" instance
There are times where I feel the need for a second account, but to be clear there is no “problem” for me here. I’m very happy for my main account to be about the things which are important to me, including being a robotics engineer and being trans. I mentioned them here because some people really like that combo and some people hate it, but that’s what my account is mainly about. I don’t want transphobes following me because they think I’m just going to post about robots.
That would limit the expression of "specific" interests to specific instances, thereby negating the advantage of a decentralised network. It would also make it rather easy to block any such "specific" instance by those who do not hold with those interests. Seeing how as blocking servers seems to already be a problem in the world of Mastodon I don't think this solution is an improvement.
