Luke Filipowicz, Lory Gil, iMore:

Downloading and installing a new OS gives you the opportunity to do some major house cleaning if you so desire. If you feel like you’d like a fresh start with macOS High Sierra, you can always opt to do a clean install: Just follow the steps below, even if you’ve already installed macOS High Sierra.

A clean install does give you a chance to shake out the leftover cruft from legacy installs. Me, I always keep several copies of backups, untouched, so I can go back and retrieve old apps/data I was sure I’d never need again.

Good post.