I still don't see why it couldn't be all one dashboard. If you're not a KDP author, you wouldn't have access to KDP stuff unless you sign up. And, if you are, no need to worry about where you need to change what. It would all be in one place. As for pen names, there's no technical reason one dashboard can't handle three, six, twelve or who knows how many pen names.
As for publishers, I don't see why they couldn't have a publisher designation and then the publisher be able to add different users (i.e., authors) that would have access only to their data. Plenty of places do that now. Like family plans on cell phones. The bill payer can access bills and so forth, and individual members can log in to see their data usage and whatnot but not see the bill.
This isn't terrible difficult stuff. Think of sites like forums which have different user levels. This sort of thing was done way back in the 1990s, probably before.
In some ways, Amazon is a very haphazard organization where things are just thrown at the wall to see what sticks and then there is no effort to tie things together in a sensible way. This is where competitors could jump in to take advantage of things. Unfortunately, the ones that have the smarts to compete probably don't have the money and the ones that have the money seemingly don't have the smarts.
Mind you, I'm not staking an anti-Amazon position here. I just think they could use some genuine competition.
