Reading the article in Japan Times, one gets an idea that the author is not very enthusiastic about idols, but interestingly, the complaints are centered around poor working conditions and compensation. There is not a word of whining about "graduation".

The best part of the article is perhaps this personal narrative:

Fast forward some four decades from the ash and rubble years. The 1980s spawned the aidoru būmu (アイドルブーム, idol boom) supported by an industry that held countless kōkai ōdishon (公開オーディション, public auditions) and employed legions of scautoman (スカウトマン, talent scouts) to comb the streets and look for that genseki (原石, unpolished gem) of looks and talent. Rumors abounded as to where exactly these scouts did their combing — some of my friends walked up and down in front of the Laforet Building in Harajuku, while others took the train to hang out on the platform of Tamagawa Gakuen-mae station — the school known for accepting the prettiest, most well-bred girls in the Kanto region. Hiroko Yakushimaru (the princess aidoru of the decade), was a Tamagawa Gakuen graduate, and back then my oldest brother’s biggest boast was that he had dated a Tamagawa girl.

Just so the gentle reader can appreciate ep.1 of Xenoglossia better.