Has anyone ever seen running “sfc /scannow” actually fix a problem?

Wondering the same about DISM commands: https://docs.microsoft.com/en-us/windows-hardware/manufactur...

Yes and it was the only thing worked after even the safe mode (win10) didn't want to start properly. Dism was kind of "not working", too.

Yes. When virus infected system files are removed by antivirus sfc/scannow run afterwards Replaces necessary now missing files.

Yes, although the last time I needed to try, I was running Windows XP.

Yes

Yes