while results do matter, our social/cultural norms and understand of human socialization ALSO matter. and in general, we recognize the maturity, life experiences, and goals of someone who's 23 are *probably* quite different than someone who's 17.
by contrast, at 65 and 59, you're both probably in similar life positions and have similar goals. is it impossible for 23 and 17 to work? no, obviously it's not. but there's such a large social, cultural, and development gap between those ages, that IMO i would not consider it a healthy norm at the societal level.