Windows without backwards compatibility is a dead end because the only reason why Windows exists is backwards compatibility and the existing user base. As an OS it is decades behind all its competitors, with a 30yo filesystem, file locking ridiculousness (which is why uninstallers and updates end up being so complex and require reboots), an antiquated central registry for settings that ends up slowing the system down over time, and a security framework so broken that you need anti-malware software running and inspecting every little thing happening on your system or you're easily compromised (everything is executable by default).

The security situation is so bad at this point that you can't trust any Windows benchmarks anymore. The benchmark suite will run on a "bare" Windows system; probably with updates and Windows Defender disabled and many other system services stopped to maximize performance and prevent background services from slowing everything down. The reality though is that on a regular user desktop all these things and a whole lot more will be enabled, resulting in vastly degraded performance compared to the benchmarks. The end user experience sucks.

Now they're forcing ads down your throat and pestering you at every turn to use more Microsoft software (e.g. trying to get you to use Edge). They've also recently included UI changes in "essential" system updates that can't easily be reverted or undone, breaking people's workflows. It's anti-user insanity and it's all because Microsoft can't actually go back to the drawing board with Windows anymore because the alternatives are just too good.

After using a Linux desktop full-time for a while, going back to Windows feels like going from having modern plumbing to pooping in the woods.