^Depends on what your definition of idols is. Personally, I think of AKB48 or Morning Musume when I hear that....some people think SNDS or those other korean groups....I don't think Perfume is an idol group. Maybe they were up till recently. Whatever they are, they sure are not a solo artist so i guess that's why they're mentioned. Although the whole article is completely jumbled mess
. Making it sound like groups are completely taking over......except when you look at the actual charts...you don't see Shoujo Jidai or Kara or Perfume. Its basically just AKB48 and the Johnny's Groups battling it out....so its not really a trend or anything....its just these 2 huge entities squeezing everyone else out of the top spots.....so that everyone else's sales look like crap compared to theirs.