One of the killers for me is the dropped support for 32-bit binaries. I don't have a gaming box, so I play Steam games on my MacBook. Lots of the games I want to play (e.g. all the BioShocks) are 32-bit.
If it hasn't been upgraded yet, then it's never going to be. The Mac isn't like iOS, it's pretty niche. You can't just throw all the software under the bus every few years and sit back smugly expecting either developers to fix all their old software or the market to create new software to fill the gap.
No 32bit Mac apps are going to be replaced with 64bit SwiftUI native apps, they're going to be replaced with Javascript apps in wrappers and your platform is going to be worse off than it would be if the dusty "old" 32bit cocoa app still ran.
It probably isn't helped by the current MacOS business model. MacOS needs to focus on things that help sell new Macs because that's where the money comes from. Back when you'd drop $129 every few years the focus could be more on the OS itself. Not that it didn't also have to sell Macs, but the OS itself was product and it isn't any longer.
Been a fan of Macs for 20 years but becoming more jaded with Apples approach to the platform.
I'm not saying it's good or bad, just explaining why (in my analysis).
Regarding Windows, I think we have yet to fully see how the movement toward "the operating system is free" will affect it. For one thing, OEMs and businesses are still paying for Windows. I'd guess direct revenue from Windows is dropping and is expected to continue to drop. But that's not the same thing as the $0 that MacOS makes (directly).
But, yes, if you want to run software from the '90s and not in a VM, then Windows is probably your OS (I think businesses are the reason for that. They have a lot of software in use that would be very disruptive/expensive to replace or move to some visualized environment.)
The cost benefit analysis should be as follows: if I know Apple is going to kill compatibility with a large range of software on a whim (ie, not because of a huge and unavoidable underlying hardware transition), I'm going to stop investing in Apple's platform, and by extension stop buying new Macs.
This is in fact what I'm doing.
Now is the first time in years where it is valid for Windows fans to mock those who use their Macs for games as it truly isn't for a majority of games that used to work just fine. Though a few games that run through the equivalent of Wine wrappers are again working.