Actually, in the early 1960s my brother and I were asking why dads were portrayed as stupid, there were exceptions but most dads were goofy, unlike the real men that we saw during the day.
Literature often has a missing or cruel father or father figure. Dickens comes to mind. The dads of Shakespeare are not normally great. There are always exceptions.
A reflection of reality or a promotion of an agenda? I think at least sometimes the former.
A good dad is such a powerful thing. We need more of them.
The only dumb guys I think of from the ‘60s were the Three Stooges.