Tell that to the people running the country! The people sitting on boards of multinational corporations! There are a lot of powerful old people. I would say the idea of "irrelevance" is pushed by the powerful onto those less powerful - it means "less able to exploit for profit" and therefore you're not marketed to as much. And a lot of ideas about cultural relevance come from advertising.

This is changing because the Baby Boomers are generally a lot wealthier than other generations and thus can be advertised to, are demanding media to feature them etc.