It can be very stupid. Depends on the software though as the registry is meant for saving user and system settings to a degree. Like Windows File Explorer makes perfect sense. As does settings for audio.
It’s generally advised to not bloat the registry wherever possible. WinSCP is a great piece of software. Unfortunately it defaults to saving to the user registry. You can change it to save to an ini file instead. By using the registry to save settings it can be jarring for the user when they’re trying to troubleshoot something. Only to find out after uninstalling and reinstalling it doesn’t start over fresh. Or if they’re trying to backup settings and data to restore with later. The registry isn’t typically included for good reason.