Is questioning the claims of not uncommon software like Spinrite, off topic? If so, Why?

It's not uncommon, and proof of that is that immediately on asking it, a commenter that uses it replied. And the website grc.com shields up is quote a popular online port scanner so it is far from an unknown website

https://superuser.com/questions/894089/does-steve-gibsons-spinrite-remove-the-need-for-backups/894091#894091