> RDP'ing into a computer with your Microsoft account is easier

Only if you use the same account on both computers. What means the GP will have to use his work account on his personal computer just to jump into another machine.

I'm confused about your hypothetical. Why would they have to do that? Could you explain that issue more?

... because they're at home without their work machine and need to check something at work?

Because their colleague wants to let them drive?

Because my sister wants some help installing a program?

There are so many situations where using a computer doesn't involve strict security protocols and heirarchies. Sometimes MS gets a little too caught up in their corporate environments.

I was asking more about your "What means the GP will have to use his work account on his personal computer just to jump into another machine", which doesn't make any sense to me. Why would they have to use their work account on their personal machine to RDP? Just use the account you're wanting to log in as. So if you're on your personal machine and want to log in to your work machine, just log in to the RDP session with the account INSERTWORKDOMAINHERE\username and your user account, and you'll be able to RDP. This works the same with local accounts or cloud accounts or other domain accounts or whatever. You don't need to have the account locally on your computer to be able to log in as that account with an RDP session.

And then all your hypotheticals speak to issues which don't involve RDP, at all, which I think shows where this disconnect is. RDP is not about sharing a currently active desktop session between two or more users, so all the hypotheticals you shared aren't the use case for RDP. RDP will transfer that console session to the new RDP connection. So say Alice is signed in to her computer locally, and then wants to ask Bob for some help. She shares the hostname for her computer, and tells Bob their login (a terrible idea regardless of it being a local or Microsoft account). Bob fires up RDP, connects using Alice's account, and now Alice's machine gets disconnected from that desktop session and is sitting at the login screen while Bob now has Alice's desktop session.

This doesn't matter if its a Microsoft account or a local account, this is just how the RDP protocol works on Windows. If you're wanting to have a screen share with the built-in Windows tools, the tool for that was Remote Assistance or Quick Assistant. The usefulness of that tool doesn't change whether using local accounts, domain accounts, or Microsoft accounts. Or just use a different tool altogether, of which there are many.

RDPing from a user in one domain into a computer with a user in another domain seems to be very broken.

So, the OP is either having problems using a cloud user RDPing into a domain, or connecting his computer into the work's domain and using the same user all the way.

It's not really broken, you just need to define the domain if it's not your current domain. Broken means it doesn't work, but it works exactly as defined. You need to tell it where you're wanting to authenticate against.

And only if you logged it at least once with the password. If you log in with the pins or other hello stuff, the computer won't have the password cached locally and won't let you in.

>RDP'ing into a computer with your Microsoft account is easier

Here is where it gets complicated, what you say is true for personal accounts and Hybrid Azure AD accounts, but it becomes super difficult with pure Azure AD accounts.

I haven't used pure Azure AD accounts from a management perspective before, and I've used it for less than a year as a user. However, I've yet to experience any sync issues personally. What kind of issues can crop up, and how?

You have to use AzureAd\[email protected] otherwise it interprets as a UPN and fun ensures. Just deployed 30+ Azure AD only devices in a clinic and that took some getting used to when elevating with UAC.

100%, and trying to train users that they need to add AzureAd\ to their login....

Also with pure Azure AD accounts you have to add each users permissions manually to each machine they need to login to since Azure AD groups don't sync down to each machine.(Correct me if I am wrong here, it could have changed since I last did a pure Azure AD install 3-4 years ago)

My issue is that my Microsoft account has a long, random password that is saved in my password vault. I never have to manually type this in because I have it linked to the Microsoft Authenticator app. But if I try to RDP to a computer with a Microsoft Account, I have to use the password to connect with the RDP app (unless I'm missing something?). My local user accounts on my home LAN have complex but easy to remember passwords so this is not usually an issue for me.

If you're already signed in, you've got access to your vault, so it's not too hard to get your password from that when doing your login for RDP. Then you can have it remember your account, or just use the password vault each time. On the plus there, then all your computers are then protected by this complex password instead of weaker passwords. Then you can use PIN, Hello, or security keys for easier sign in locally. Your account is still protected by your complex password, the alternative login methods are local only and have short guess attempts.

I haven't tried but I think these days you can actually authenticate RDP with a security key associated with the account.