Is that a rating, a film or a domain?

I am not sure this new high level domain of .xxx makes any sense. When I say triple x to my 21 year old son it makes him think of the Vin Diesel film. If I said it to my younger children it might not mean anything to them at all. I think the last time I said rated x to them they didn't know what I meant. I, of course, had forgotten about the NC17 rating and thought they would know I meant a film with very strong sexual content.

If the generation growing up using the internet doesn't understand what xxx means why bother using it? Doesn't that seem like twentieth century thinking?