Not seeing a problem here either. It's free to create an account on however many instances and it lends itself to per-topic pseudonyms which is probably better

Not seeing a problem here either. It's free to create an account on however many instances and it lends itself to per-topic pseudonyms which is probably better than one identity everywhere anyway unless you're explicitly trying to build a self-brand. Even in the case of a single identity everywhere, it gives your followers a way to control which types of posts they see from you. Maybe they don't care about my explorations in UI design and programming and just want to see what pastries I've been cooking lately, in which case they can follow my account on a cooking-oriented Mastodon instance. That's actually one of my minor gripes with Twitter; it had no way to filter for topic which meant that even though I followed people I had an interest in my timeline still had a lot of stuff in it I didn't care about.