Quite a few cultures hold that the role of sex in the good life ( ie. a committed relationship ) is too important to allow for uninformed sexual fumbling.

Most all cultures have assumed, quite rightly, that good sexual techniques must be taught. And so most all assume that there will be a mentor who will teach this prior to any permanent emotional attachment.

The idea that performance anxiety could interfere with learning from the one you emotionally want to please would require that the rehearsal parter NOT be someone you are in a committed emotional relationship with.

Further those cultures didn't seem to exist in a world which was fraught with young men later proclaiming regret for such instruction outside of marriage, nor suffering abandonment issues because their first partner was not their future spouse.

We expect that the groom will have learned from a dance instructor who would not choose him outside of her teaching role PRIOR to dancing with his bride at his wedding. We do not assume that he will just learn how to dance with his bride spontaneously when the desire to do so grips him. And yet we leave the ( preferably for the innocence fetishist ) virginal bride and groom to fumble about it on their own.

Oh, we assume that if they are exposed to enough charts and graphs that somehow, magically, the information about physical sensations will be transmitted through the visuals and writing. "An orgasm is like a sneeze."

I believe that we all know that good sex only happens because of prior physical experiences. Blue Lagoon is a fiction.

The sexual revolution didn't make sex better because of how-to manuals. Oh, those helped. But it was the decriminalization of pre-marital sex that made it possible for the ( so common as to be clichéd ) mediocre first sex act to occur PRIOR to the conjugal bed. And again, just how many who married someone other that their first partner are running around feeling devastated that they made informed choices rather than committing to a permanent binding relationship without prior experience?

Sex is a physical act. Like all physical "performances" it cannot be learned without performing it through rehearsal.

Cookbooks are a good thing too.

But the reader of cookbooks who has never performed the act of cooking nor has adjusted the recipe to suit tastes they only can know by tasting should not be assumed to KNOW what it means to cook.

Frank Zappa once said, "Writing about music is like dancing about architecture."

Dante