That sounds way too idealistic and simple to me, and it doesn't really fit with past experiences.
Riot's balance history is mainly nerf-focused. Throughout all of seasons 1-3, and for a lot of season 4, they balanced probably 66% of the time with nerfs. It didn't fix the problems. Some champions still went chronically unplayed until they finally hit 55% winrates, saw play until they got nerfed for being OP, then fell off of the face of the earth again (Skarner actually did exactly this in season 4 following his second mini-rework / balance change). At some point, they had to concede that just playing nerf whack-a-mole wasn't working.
Skarner wasn't getting played no matter who got nerfed, because he brought nothing unique to the table. He was the very model of a boring champion with exactly one unique mechanic that wasn't really that unique. Unless you made him OP (and he already had a 52% winrate so you really to tune it up), he wasn't going to see play. Skarner is my favorite champion, but I will still tell you that I would never have considered him worth picking unless every other champion in his class sucked. He was either going to be the strongest champion, or he was not going to see play. There was no middle ground.
Some champions are poorly designed and won't see play until their design problems are fixed. A lot of the "balanced" champions are ones who don't actually do anything that other champions don't. They can technically be played, but there is never any strategic reason to do so because other champions do every aspect of their role at least as well as they do. Multiple champions share the same role and the same basic mechanics, so whichever one is strongest sees play while the others don't, and there will always be a strongest because their kits aren't differentiated enough for them to be worth picking in different situations. That's the kind of problem that calls for reworks, and that is exactly the problem the juggernauts had. They all competed with other champions for the exact same role, played in the exact same way.
The juggernauts are much better designed now. They actually serve unique purposes in the game. Yeah, they're overtuned, but that can be fixed and they'll still be worth playing. No numbers tuning would ever have fixed old Darius, Garen, Skarner or Morde.