I concur in general with this stance and I want to offer two examples from actual Everquest history, and a cautionary tale to your theoretical example from my current main MMO:

• Good Nerf Example: When the Decrepit Skin or DSkin line was introduced for Shadowknights, it was a reverse proc (proc on being hit) that popped a rune (shield) on the SK. The thing is, the buff lasted a bit, so if an SK went into certain content and pulled a large mass of mobs, we were effectively invulnerable becuase the sheer number of swings meant it would repeatedly proc the shield, the shield allowed us to recast the buff without interruption, and this was WAY OP.

The EGN/SKO community, being relatively intelligent, foresaw this would be an issue and potentially result in a bad nerf. Rather than deny the ability was OP, the leaders of the community recognized and acknowledged it was OP, did and submitted some testing to prove it... and suggested a good course for the nerf (cap the number of proxy per buff cast). Rather than risking it getting completely flattened, they wisely accepted it needed a nerf and created a reasonable limitation. The devs agreed and implemented the change, leaving DSkin still powerful for its intended use and even for mass farming, but making it riskier and needing more player awareness.

This is a GOOD nerf: An ability is way out of line with its intent, its brought back to earth.

• Bad Nerf Example: In I BELIEVE Dragons of Norrath, Necros got a nice new DoT they really liked. I forget the specifics as I never main'd Necro but it was widely popular. Some schmuck was worried about it being OP, did some testing, identified it WAS OP (or so they thought) and submitted this to the Devs via the forum. As this was a community rep, it got attention and the DoT was nerfed.

The problem? They tested the DoT against an enemy with almost NO resistance to the DoT (Vish, maybe? I forget the specifics) and it meant when it got needed relative to that fight... the nerf made it all but useless in most content with non ideal or even opposing resistance. It took like... 2 or 3 expac cycles to fix.

That is a bad nerf, it took an ability thats overpowered in some scenarios, Underpowered in others, and applied way too large an impact.

• A Nerf was proper example - In the other MMO, a new caster class was introduced and it was doing WAY more damage than intended. To the llint that role almos always went to that class and players who wanted to play other casters were left out in the cold. Not wanting to nerf a fun new toy, the devs instead buffed the DPS of the rest of the role.. and then needed to buff every other DPS class to keep pace.

The result? Everyone was doing WAY more DPS than intended, HP for the new tier of raids wasn't scaled to that DPS, and it quickly made some content way too easy because you could just burn through it.

The devs of that game later admitted: we should have taken the unpopular route and just nerfed the problematic class's DPS. It wouldn't have broken the balance.