I worked at Microsoft during Windows 7 & 8. There was a strict edict that minimum hardware requirements would not be increased and we were expected to improve performance on the same hardware.
Have you actually seen windows get worse over the last ~9 years since vista or is this an impression that's just too hard to shake?
W7 performed great and W8.1 (I skipped 8) only improved upon that speed and power efficiency. W8.1 with Classic Shell and before Metro spread throughout the system was my favorite OS-stays-out-of-the-way Windows.
Disabling desktop composition (the Desktop Window Manager/Aero) was a supported option on Windows 7, but is not an option for W8 and above. Windows 8 also requires NX and SSE2 support, which leaves out 2003/2004-era P4 and Athlon XPs.
Interestingly, disabling compositing doesn't mean increasing system requirements, because Windows 8 can do it in software. A GPU will improve your experience, however.
And well, he specifically said that operating systems go through bloat and debloat phases over and over. XP to Vista was quite a step towards bloat. 7, 8, 8.1 partially debloated that again. 10 with its telemetry and increased online focus seems to chew on that, again.
But even then, it's not like Windows is a miraculous feat of efficiency. There's functionally equivalent Linux systems with down to a quarter of the resource usage.
If Microsoft put any effort into some tooling people could use (without taking a week off work to study to learn how they work, what claims in the documentation are true vs lies, etc) discover wtf is slowing down their system and why, they might get a bit more respect from the technical community.
It's win10 enterprise LTSB but still damn impressive.