I suppose it might have been acceptable in some areas but it certainly wasn't in mine.
At 15, myself and the overwhelming majority of my school year didn't have boyfriend's, though we were definitely aware of boys!
When some did when they were 16/17/18 the boys were always within a year or two.
We were not particularly innocent I think, because we certainly would have known any guys 5-10 years older that would sniff around teens, are creeps.
Thankfully we all would have come from homes where parents would have been rightfully appalled and would have stopped it, I have NO doubt.
I think vulnerable girls were, and are, susceptible to these predatory types that either can't form a relationship with a peer, are controlling, want to appear worldly, or just simply like young girls.
IMO it is ALWAYS creepy, and no parent with a functioning brain, now, or 40 years ago, would have found it acceptable.
OP, I can well imagine you have the Ick looking back.
15 year olds now are far more clued in and yet it still would be wholly unacceptable.
The imbalance is certainly not in a 15 year olds interest.
The difference in maturity between 15 and 20 is simply enormous.
40 years ago involved, caring parents may not have know the shit the church was up to etc., but they knew 15 year old girls should not be intimate with 23 year olds.🙄
Suggesting otherwise is a cop out IMO.