"although Microsoft won't stop you from installing them."
You're completely missing the point - Microsoft won't stop you installing them but more importantly, it won't prevent you from un-installing them and going back to what did work. Ditto Android and Linux.
It's perfectly reasonable that the newest software won't run well on an older machine. What is not reasonable is to actively prevent you from downgrading when you find out it won't.
When Apple was producing unquestionably the best tablets, they could bully their customers like that. They now have strong competition. My mother now has a tablet from another maker and I have one on the way. I will not be held hostage to Apple's fortune.
My interest in this forum now is to flog the two iPad2s in decent working order so I continue to follow gratefully those who try to help.