its not really a "trick" or "strategy"
This is a basic tactic that has been around for a long time and is part of how you deal with champs like katarina, fizz, or akali.
its a lot harder on AP champs though, against an AD champ like Quinn youre just not going to have early advantage, that's just all it is. I did this as cait once to an azir and I absolutely shat on him but what the video doesn't tell you is that if you do this then odds are you are not playing a conventional midlaner or toplaner meant to do their typical jobs.
another thing to consider is that a champ like Quinn doing this wont mean that she can ignore a full combo from leblanc. You are not really getting a permanent level advantage just repeated temporary ones which is something you will have seen in nearly every match you've ever played, all this does is make the advantage more exploitable by widening the window.
This is not a fancy new trick, this is the basics. A lot of people never think about how leveling actually works in this game or tries to put any math on it or anything. That's why they think theres no point to jungling in URF mode for example.