Cute story: I once said on k-pop forum that just because x group was popular didn't mean they were good. My reason was because a lot of stans I was noticing were saying that more popular groups were good and that their popularity proved that and as such less popular groups weren't as good... Anyway pressed stans told me to f--k off as they did not really understand my point.
I don't think we should even localize this to k-pop since I'm sure we can all think of popular western songs that we extremely hate and even artists. I won't mention any since I don't want a wp for shading artists... but we know who I'm talking about. But to the point: there are groups or artists that I could mention from prior generations that weren't as well known that you may not know if you didn't come into k-pop during that time period, such as Heo Young Saeng; while if I mention Taeyeon or Junsu you would know what I was referring to... it Doesn't mean that Taeyeon and Junsu are better musicians than Heo Young Saeng because they are more popular. Some people [hipsters] will maintain that the best musicians are the more obscure ones. That isn't true either.
Lets try an exercise to prove a point. Lets say that popular = good. There was a group called Bom that was short lived. Given that they disbanded rather quickly and have not attained to an enhanced level of popularity they must have sucked, right??? Well you'd have to say that Mino from Winner isn't talented because before he debuted with Winner he was a member of BoM..