Hank is also mostly a product of his environment, yet a caring father that accepts his family for who they are. If all boomers were like Hank Hill, we'd all be happy.
It mostly comes from a point of not understanding Bobby. That boy might not be right in his eyes but he loves and supports him. Even if he should know more about propane and propane accessories.
King of the Hill started in 1997, Hank is 41, that means he would have been born in 1956 of the series is taking place at the same time it started (there's a millennium episode so that pretty much confirms it), it's just an issue of characters not aging in animated series.