I totally agree, I do look at remote profiles myself, but I've noticed novice users really don't like it.
They tend to get confused when they suddenly have to start entering their password again, when the server may look completely different (e.g. on a PeerTube or PixelFed account).
Just seems easier for new users if everything seems to happen seamlessly within their server, without any more logins required?
But yes there's no perfect solution for this because even a backfill would only give a limited view compared to the remote copy.