"Ageism" is vile. We've been programmed in the USA to value youth even above character, sadly. As a result, Ageism is what one might call "am acceptable bigotry" in social circles. Not good. Though Ageism works both against youth and elders, it Most often negatively impacts Elders.
One good reason too stop it, is that continuing it scares the youth too much about a pretty natural process in their lives.