If your adc manages not to die and bot goes even, he gets out of laning phase being a monster like 2 or 3 lvls over the enemy adc. Plus, the enemy jungler will starve and get far behind, probably enemy mid laner too because of being permaganked.
I dont think this strategy has something to do with the current state of the game, I guess it would work more or less in any season. Support leeching the adc is a BIG handicap. I've thought about that kind of strategies a lot, but unfortunately I'm not a skilled player plus I dont have the knowledge, so I guess I wouldnt make it work. Feels bad man.