The technique with Grigri is easy to learn compared to some other tools especially during its initial release, and TBH I don't recall ever saw anybody using it

The technique with Grigri is easy to learn compared to some other tools especially during its initial release, and TBH I don't recall ever saw anybody using it incorrectly since it would always prompt a strong reaction from anybody else just passing by. But it has to be learned, it doesn't come somehow magically on its own. Its not fully auto-blocking, if angle of outgoing rope is 'right' it doesn't block at all. What that guy did on the video looks absolutely ridiculous from first second. Zero visual contact, too much slack (so that he doesn't have to look up), very little safety even without actual accident. When in practice there should be 100% visual contact, or at least 95% and fully covering all non-easy parts. It strains the neck massively but for that there are those cheap periscope glasses, I got mine for 10 bucks on aliexpress and they work fine enough for 10 years. The basic technique means rope is 100% held by either hand at correct angle regardless what you need to do apart from holding it.