But it is 17 in most states and even 16 in others so Seinfeld wasn't doing anything illegal. Not saying it's a good look for him. BTW, none of those technical advancements were made because of the age of consent laws.
Its not always about what's illegal. If in New York the age of consent was 17 why did Seinfeld make sure every media oulet knew he didn't "date" her until she was 18? Because public opinion and perception matters.
You're correct, no advances were made because of age of consent laws. However we progressed in our thinking, learning and understanding and because of that we've changed.
As recently as the 1950's women were persuaded to become a married housewife by 18. As recently as the 1970's a husband could physically beat up his wife and the police wouldn't get involved. Society changes as we advance.
We now know the human brain isnt fully developed until 25. 100 years ago that wasnt the case.
None of it matters becuase at the rate society is progressing pedophilia may be recognized as a sexual orientation as opposed to a deviancy.