This is not, btw, so much a feature of oldschool gaming as it is a questionable DMing style. Which was, to be fair, really *really* common back then. But just like game design has progressed and improved, so too has the art of running games.
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Well, imagine 3LBBs OD&D, pre-Greyhawk. The characters, short of a couple divination spells and items, don't have any input. The players are told exactly what they see and what happens when they do something. Now, the DM can make all the elements of the environment totally obvious, and rely purely on puzzle-building. The original sorts of traps worked like this:
DM - As you make your way down the hallway, you notice there are some small holes in the walls ahead at about waist height.
Player - I stop and raise my hand. The dwarf hands me the 10' pole and, standing back from the nearest holes, I slowly begin to probe the flagstones of the floor ahead.
DM - Right, you soon notice that your pole bumps against a fine piece of wire stretched across the way at shin height.
It becomes just procedural, though obviously if the trap is a Rube Goldberg then the players have to dope out which levers to pull or whatever to allow safe passage, etc.
The problem is it is vastly tempting, and almost inevitable, that the DM will add in some twist, like the hole in the ceiling positioned right where you'd stand if you were probing with a 10' pole, but concealed by some moss so that the characters have to go study the ceiling (explicitly of course) or else gotcha! While some DM somewhere NEVER EVER relied on this trick, all the human DMs (including Gygax himself) relied on it heavily and it was considered a standard part of the canon of DMing tricks. A game of that ilk without those tricks very quickly turned stale, there's only so many puzzles the DM can invent.
In any case Greyhawk came along and the whole "player vs character" debate began. So, yeah, in some idealized sense you are correct, but in actuality most of OD&D is about 'pixel bitching' (at least that aspect of it, there's of course RP and other elements to the game).