I don't think that "advertisers" are as homogenous as you portray them here; generally, they have specific products that they are marketing to specific demographics, which sometimes includes denture paste.
True, but teens and young adults are much harder to reach through "traditional" advertising and much more valuable because advertisers can influence purchasing habits that will last a lifetime. As a group, they are worth a lot more to an advertising supported business than the 65-70 crowd.
Indeed, but it's no secret that most mainstream advertising skews towards a much younger demographic.
It's very possible to have success marketing denture paste and products to older people. But if Facebook does hemorrhage teens, advertisers will take notice. And right now Facebook is advertising. That's going to have an impact.
