I'm new to fediverse. For a long time I assumed it would be possible to have a single identity separate from the ActivityPub instance I'm using and tried to figure out what am I missing. Recently, I figured out that it was not the case. People generally have multiple accounts for interacting with different aspects of fediverse. It still bothers me a bit. So I did a search and found this note from 2018 that summarizes my thoughts very well.

I'm wondering if there are others thinking about this, or having multiple accounts has been accepted as the "correct" way of interacting with fediverse?

I think separating identity from the instances would really be a step forward, but as I said, I'm new to this and maybe there are things I don't understand?