People use them less frequently, so they don’t type the credentials as often?

Yeah, I can't even log into my MS account to do MSDN stuff. Microsoft support: "Use any non-microsoft browser". I ended up creating a "personal" and "work/school" account as part of the process, and I think I have to pretend it's the personal account when I log in. I get the feeling I was creating two accounts - a live account and one related to the MSDN side of things, and they are linked in some way. Why...just why? Why can't I just create one account, and don't come up with this specious personal/private distinction. I wonder if they're making decisions on products etc based on what sort of users they think they're dealing with. Personal MSDN customers?

Its compounded by the fact that we all had Lumias (I still like the UX over anything out today) and some used existing hotmail/live accounts while others created new ones, even though they had existing ones. At this point they have no idea what they used any more for what and it's often a hassle when they switch phones or get logged out.

On first glance, I would think no.

But in my experience even though I have 5x as many Google accounts as Microsoft ones (across several organizations and institutions) I spend almost no time confused on whether I'm logging into an account that I created, was created for me, was merged with another account, or is an institutional account that was created with a personal email.

I use a password manager for all of them. The only difference I can think of is the UX flow on Microsoft's sign-in page.

Sorry, maybe I am missing something here. For local admin, I agree re context switching etc. But for O365 admin, we have a similar setup and I admin O365 through a separate container tab or Powershell where you need to connect to Azure separately anyways. Seems straightforward to me.