Re: The Question Remains....
""you would pay literally any money to get anything even remotely comparable to SCCM or AD on your Windows-disabled PCs. And you will fail, because there's no such product.""
No, all you need to do is focus on "what I need these workstations to do", not on what AD or SCCM can do.
See the issue is that you know how to use SCCM and AD, but nothing else, SCCM and AD make sense to you, but anything else you come across you instinctively just run a checklist comparison and of course on Windows any MS solution wins.
You remind me of someone I had to show that you can have ACLs on Linux that behave like on Windows, not twice but four times, and his argument in the end was that it wasn't as sophisticated as on Windows. The point that you could achieve exactly the same functionality was of no value to him.
Think that perhaps your issue is that you do not know how to do something in Linux (and any other platform) and not necessarily that Linux can't do that.
The only area where Linux lacks is if you are locked-in With a MS only technology, office documents, Exchange PIM (for email Exchange is a bad joke) or Windows-only applications.
One thing that I find funny is when people confuse what you can do with Shell scripts in Linux with what's possible on Windows (even with powershell) and conclude that because you have to write scripts the platform is of lesser value (tip is totally the contrary).