I'm guessing there's a more general name for the concept, but drawing a blank.
This is essentially the reason advertisers tend to target the young - those over a certain age are more set in their ways and not looking for new options.
It's called "exploration vs exploitation". Unless you meant the idea that older people need to explore less because they're already done it. I don't think there's a name for that specific idea.
I originally searched for "exploration vs exploitation" but that lead to the "multi-armed bandit problem" on wikipedia, so I went with that on my post above.
I do that "exploration vs exploitation" is a better name for it though.
Yes, the general name is "ageism". This has nothing to do with young versus old. Younger people are funnelled to a small number of larger sites just as much as older people.
This is essentially the reason advertisers tend to target the young - those over a certain age are more set in their ways and not looking for new options.