OK why is MacOS still the ONLY OS that executes this flawlessly and smoothly every single time no matter what is running?

My system76, with vanilla Ubuntu LTS does this perfectly for years. As did my thinkpad before this and the thinkpad before that. Always Ubuntu LTS, without big modifications.

The last time I had 'sleep' issues was with MySQL crashing when it woke up, and it found the os time changed without its internal clock moving forward. IIRC that was over ten years ago.

My main computer for last few years has been an Asus X305 laptop, using Ubuntu 14.04 with the i3 tiling window manager (i.e., there is no desktop). It's best computing environment I've had since I started out on a TRS-80 in 1979.

My i3 setup is not tweaked to auto-sleep on lid close. I'm sure it would have been easy to set up when I installed i3 back in 2015, since the sleep-on-close worked with Ubuntu's Unity desktop. Instead, when I installed i3 I attached sleep function to a hotkey, so before I close the lid I press the hotkey (if I want system to sleep). It is totally not a big deal. The system does autoresume when I open lid, which it also did in Unity environment. But if it didn't that would also not be a big deal.

To me the idea that someone would reject a superior system if it didn't auto-sleep (or auto-resume) on lid close/open is bizarre. I actually prefer to manually control with a hotkey.

It does everytime on my XPS 13

Oh that's a good point. It doesn't always. I'd say 2/3 times, 1/3 times something else happens. Usually I manually hibernate first.

Also connecting two HDMI monitors is wonky, monitor 2 flickers once every other minute or so (it's worth it) and sometimes isn't detected.

My HP Pavilion laptop did this perfectly several years ago, at which point I didn't even know how "lucky" I was that it all worked. Fedora/KDE was the distro.