Classic D&D prescribed one-minute combat rounds. So does that mean it took a whole minute to swing a sword? No way. One round - or so the story goes - consisted of multiple thrusts and parries, meaning each attack roll was (at least potentially) the culmination of several such actions. Abstracted to be sure; but we were good with that because the game was so damned awesome we didn't care. Nowadays, six-second rounds (or thereabouts) are preferred, but it wasn't always so, and I blame books and wargaming:
Ok, so books. Fantasy has long been a literary genre; but anyone born after 1970, and certainly after 1980, might not appreciate just how little of it there was outside the pages of books. Dragons and wizards were difficult and expensive to render, so movies generally avoided them (with notable exceptions, obviously). At any rate, the genre wasn't mainstream by any stretch of the imagination. But we had literature. From vintage storybooks to pulp barbarians to Tolkien (among others), books gave what the mainstream couldn't...
And books are abstracted much like those combat rounds. Consider this:
Thorgir cut through a jungle of writhing limbs and snarling faces. His blade drew sweeping, gruesome arcs and still the things came, eager to kill or die in a suicidal last attempt.
The above isn't blow-by-blow. Fiction isn't photorealistic, except when it is. But the best writing lets the reader's imagination do some of the heavy lifting. Poor Thorgir is up to his ass in foes; and one can easily imagine the blood flying with each swing. Wargamers raised on the tales of Howard and Tolkien were doubtless predisposed to accept this. Now I know that books are still a thing. I'm not an old man yelling at clouds just yet. But modern hobbyists have access to entire channels devoted to fantasy, so expectations may differ.
Fine, but what about wargaming? I'll only suggest that when one figure on the tabletop equals ten (or more) troops on the battlefield, you aren't rolling for each one. This is D&D on a grand scale. One round equals many blows from many combatants, each performing a melee of enormous scope - and with longer combat rounds to match. D&D's first generation was likewise programmed to accept this, especially since characters were also seen as far more disposable. Anyway, as more individuality crept in, so did changes to the rules...
Characters got more hit points. Clerics got more spells. A stab at survivability in service to an ongoing narrative became the standard as more non-wargamers signed on. Add the inevitable influence of movies and television, where each strike is captured in precise detail and - huzzah - one roll of the dice equals one attack in a blow-by-blow narrative.
Of course, it's not so simple. Back in 1978, we were already narrating attack rolls in rich detail, so the shift was probably inevitable because players, being human, became attached to their characters. Even so, we can't discount the way in which popular media influences expectations. Movies, television - and now computer games - have greatly changed how we consume fantasy; and it's hard to imagine this hasn't made a difference. But young or old, the mainstreaming of fantasy is a good thing, and our hobby only better for the trend...