I agree with your take on that.
If you can’t take care of your Windows install, you don’t know what you are doing. Registry cleaners, drive cleaners, uninstalls, disk defragmenters, etc. all help you keep your current install going for years. Couple that with backups, and you are golden.
In my experience these do more harm than they help, especially registry cleaners.
I don't want to join any pissing contests, I've only owned computers since '96 but I've had a lot of experience with broken computers. I think I'm jinxed ;-)