> assuming old people are dumb

Not just old people. Hackernews skews technical and seems to mostly interact with other technical people.

There are people in their 30's, 40's and 50's who don't own a computer at all (other than a smartphone), don't interact with computers on a regular basis, and almost exclusively use the built-in talk/text/browser apps that come pre-installed.

It may be a relatively small percentage of the adult population in the US, but it is still many millions of people.