It was more about system optimization tools like Ccleaner and defragging your hard drive as self optimization of OS didn't come in until Windows 7. You can do a clean install but ypu'll have hours and hours of updates to download. Win 7 and 10 are better OS versions.
A clean installation is also effective for mental health.
Suppose the earth is a system disk. In the process of evolution, the problems of large amounts of waste and unmanageable harmful effects cannot be avoided. The idea is that if you are worried about those solutions, resetting everything will reduce your physical and mental fatigue.