It's far simpler.
90% of players are not meta breakers.
Every class of champion has hard counters and utility counters who can shut down performance.
Who does Garen/Darius Fear?
It's generally Bot laners. They generally control and hard counter most top lane champions.
Because one group decided to stay in one lane and one group decided to stay in another, the issue has never arisen significantly.
The only times the issue gets an identity is when some high profile matches contain them and other players begin to mimic it loudly.
After Sona and Soraka, expect a cycle of Zyra/Brand/Lulu Top.
It's very likely that Garen's rework has a big impact on why people are doing it a little more now. His attack speed/offensive build that he uses now basically means to win games, you have to shut him down or deprive him at level 1. Otherwise, he just runs around shredding people mid/late game. Most melee range champions dont do this to him. Healing is one of the biggest counters to Garen's kit, as is self mobility/range. It likely started there, and spread to other champion matchups.
Drake priority DOES play a role. The game pacing right now is generally so fast that underleveled junglers + drake cooldowns generally force most jungler rotations to stay bot or lose, so what used to be a goofy deviant play in top lane is now a legitimate tactic, because the threat of a 2v1 top lane gank has diminished so much (In the past if top bruisers wanted to kill a top lane enchanter, all they generally needed was a jungle gank, and many times they could even kill the enchanter in turret dives)
, find their way back Toplane, again
