I don't think you any schools teaches not to reuse things. They teach you not to use things you aren't allowed to use. Did they tell you to build your own computers and to make your own transistors? Think about what you were taught, don't just blindly repeat what you thought you heard.

Again, there isn't any evidence. Why would this be? I use the same basic rules for every os I manage, and guess what? I never have to reinstall. Never.

I don't think this is true. And I don't think linux is safer. Just give some evidence, please. Or don't say talk about what you don't know. Please.

In my experience, MS apps generally don't have this problem. Never saw an application that I wasn't able to run as normal user. It sometimes requires a lot of pain (regmon, filemon, procmon...), I must admit. But nowadays app are far better that they used to do. Anyway, the problem is then in the application, not in windows.

Malware is installed by clueless users, it's not something that comes out of nowhere. Run as admin and click on "yes" on every possible warning and you'll get just that. Malware isn't mandatory.

I managed +- 100 computers in a university lab. Only reinstalled once, a computer with bad memory chips which were corrupting data, so corrupted windows and antivirus updates had caused a real nightmare. I don't see why reinstalling should help. If you have a problem, it often has a cause. If you reinstall, there is a big probability that you'll have the same problems, because you'll probably do the same things. Understand your problems and their causes and solve them, instead of wiping everything just to do the same thing over and over again. Corrupted installations? Run as admin and don't update, and your box will be corrupted. Don't do it and it probably won't. If you don't run as root on linux, why do it in windows? You don't have to, I didn't for years and have always had clean computers with fixable problems.