Oh dear, I didn't mean to get into a secondary row about the Bay City Rollers! ;o)

To be fair, I just grabbed that name out of the air as an example of massive popularity, although they are commonly characterised as musically poor/average. Just to illustrate the point that large audience numbers/ audience members dancing does not necessarily correlate to superior quality. There has been a lot of inferior crap marketed to the masses which has sold millions. (Granted, there are also many fantastic artists who have achieved mass success).