Thanks for explaining that further. That all makes sense.
I was looking at your post from the perspective of "where are your keys"? And being a desktop-client developer I wasn't thinking of the model that your client may be out on the network somewhere (web hosted apps).
Your identity provider should certainly be the closest thing to you, and yes you take that identity out for a spin on the town. Nos2x is like your identity provider. Gossip as a local desktop client is a client and identity provider tied together. Nostrum served from a webserver could be an identity provider for people who are willing to trust dynamically served web content with their keys. nos2x/alby feeding nostrum being preferred IMHO.
I can't imagine having more than a small handful of identities. Firefox has Multi-Account Containers that work just like this. Websites see very different identies when browsed from those containers. I've only ever had about 6 or 7 such identities, and managed client-side has worked out for me.
However, if you want to use many different clients with those same identities, and you have a lot of extra functionality surrounding those identities, then combining the client with the identity provider kind of locks you in. I don't want to lock anybody in. So I'm open to having a pluggable indentity provider in gossip, but there has to be (among others) a local desktop provider that is open source that I can read and learn to trust.