They do but it depends on the person. Age is usually rated in a general sense but of course there are some people who watch shows completely out of their age rating group.
My Sister watched Archer and I tried it but not my kind of show. I know I have watched shows like Southpark, Family Guy, American Dad, ect. In the past.
Who knows, maybe ill get tired of shows I tend to watch now and get into another animated show. But overall, Im not the kind of person who watches them. Usually I was simply because of another family or friend watches them and I sort of got into it too.
What I cannot get into is Anime even though many people seem to now days. Im 20 now and im more willing to bend and watch shows that are different just to spend time with family and friends.