I'd love it if there were never any registry problems. What concerns me is the sudden change in the pattern. It's as though a city street that's normally clogged with traffic, day in and day out, one day is suddenly empty. One wonders why. Something's up. SFC and DISM have found nothing, so at least from that angle, it's not a damaged Windows. But what?
Faulty/damaged RAM can cause corruption from my past experience, so perhaps that's the difference.
Other than that most registry "problems" are caused by uninstalling software that leaves something behind that a registry cleaner will deem invalid and offer to clean, and when opening a folder containing files with no program associated with them to open them (such as Firefox addons/extension which are .XPI files, etc.).