Being good in the meta does not mean the champion shouldn't get nerfed

Title. Fact of the matter is that if a champion is too good, it'll block out other picks from being played and nobody will rotate metas because that champion/subset of champions will remain too good.

Are there limitations? Yes. Unless a champion is pulling hotfix-worthy numbers, it's probably worth waiting a patch (in League time, so about 2 weeks) to see if anything changes. If after 2 weeks the meta doesn't adapt and evolve, then it's a good idea to look at the champion.

Look at how the champion is thriving. There are 2 different ways a champion can get strong. The first is through circumventing a key weakness in the champion. For example, E max double Doran's Zz'Rot Nasus (when it was a thing) circumvented his weak early game by guaranteeing hard shove and 10 cs/min to get him farmed up enough for mid-game skirmishes. The other is through accentuating strengths, such as Athene's + season 4 artillery champions (Ziggs, Xerath, and yes old Gragas was an artillery mage too. It was gross). Again, unless the numbers are hotfix-worthy, a meta that accentuates strengths is probably not that bad (in my defense for mentioning s4, Athene's was pretty hotfix worthy). It means you'll be playing champions that like these changes and so a lot of the picks that counter them that don't use that meta won't be seen. That's just how these meta abusing champions appear so dominant.

The real issue is circumventing weaknesses. Champions need real weaknesses or they end up being ever-present picks that are just too good against the rest due to their generalist nature and nothing else becomes worth picking.

So if this criteria is met, it's usually a good idea to look at nerfs for the champion, even if it's "just the meta."