The base methods for 1e wasn't 3d6 as alluded to in the OP, it was the now main stream 4d6k1 arranged to suit
"Method I: All scores are recorded and arranged in the order the player desires. 4d6 are rolled, and the lowest die (or one of the lower) is discarded." Although the other methods were just as valid, method 1 took rank just cos it was first!
In addition Gygax had this advice for PCs "Furthermore, it is usually essential to the character's survival to be exceptional (with a rating of 15 or above) in no fewer than two ability characteristics. " And that was in the PHB no less, so player's could reasonably ask for re rolls until they got that!