There are too many types of buttons in the web, buttons not always look like “buttons”, for example, sometimes they are just icons. And it’s weird that for you links that look like buttons and have the correct affordance should have the hand cursor and buttons that look the same that those links, shouldn’t.
I understand your point, “why the web should be any different to OSs and native apps?”, but it happened. You cited Apple and Microsoft, but in their sites they use the hand cursor for all their buttons.
In the web all buttons (links and buttons) have the pointer, and I will continue to stick to that common pattern that users are used to when using the web.
Nice read, thanks.