Linux encourages users to send patches while Microsoft is the sole company that can modify Windows.
It’s very common to see patches from Google/Meta/Cloudflare/Amazon squeezing more performance for their particular use cases. That benefits everyone in the end.
Microsoft on the other hand is more concerned about its enterprise sales and overall profits. So they don’t care that much. Windows 7 was horribly bloated, and they didn’t address until Windows 8 because they had to, because they realized it was too bloated to run on their new tablet PCs so they had to do something about it.
Apple cares a lot, because their thing is energy efficient fanless netbooks, and phones, and tablets. macOS and iOS are very close in how they work, so Apple has all the incentive to keep it efficient because their software will also affect the hardware side of the business. Microsoft doesn’t, it’s the hardware partners that get stuck dealing with it.
The NT kernel is fairly good, it just doesn’t get the attention it deserves. Microsoft mostly add features on top of older features, they never go in and be like “this sucks” and rewrite a feature, because that’s very risky to do and may break millions of applications and affect their bottomline. Linux doesn’t have to care about that.
I’d say, if Windows was open-source, we’d have some pretty solid Windows distributions because the community would care to go in and fix a ton of bottlenecks that aren’t worth it for Microsoft as a company to even bother reviewing the patches let alone develop and test them. It’s much more lucrative for them to release AI crap like Copilot than make Windows 10% snappier. Because most Windows users are corporate people that makes decisions based on marketing and business items than being an enjoyable experience. Less frustrated users? Nah. More productive employees with crappy AI features that barely works? Hell yeah 🤑
TL;DR: Windows sucks because of Microsoft’s business interests don’t require Windows to be that good, merely good enough.