Snide tackles and surrounding the ref.

Jokes aside, you talk about it like its a new thing, but its not really. SAF's treble winners did it, and the Italians have been doing it for decades.
There's always been the odd moment before where it happened, but Pep's Barca turned it into a significant tactic and popularized it. It's been part of the reason his teams managed to play such a high line and attacking style, as any time the opposition won the ball back and looked like they MIGHT be able to get in behind the midfield one or another of their players would just 'accidentally' trip the player instead of winning the ball. Since the refs rarely actually punish it properly, everybody else has to do the same thing or they are putting themselves at a disadvantage.