I think the continuous integration is key to emphasise. HTML Tidy does validation as its default action (tidy <html file>), but unlike this, it doesn't seem to

I think the continuous integration is key to emphasise. HTML Tidy does validation as its default action (tidy <html file>), but unlike this, it doesn't seem to be able to target an entire directory (html5validator --root <directory of html files>), so there's another difference there.