Randall is somewhat aghast by this, as well he should be. It seems terrible to me as well - I have a sad memory of giving a friend playing in one of my early AD&D2e games 30 seconds to find a given rule, or else I would make something up on the spot; he flipped so quickly through my copy of the PHB that he ripped a page nearly in half.
I can't say that I never have to ask a player to check the rules on something - I am not that well acquainted with the precise rules of most of the cleric/wizard spells beyond "cure light wounds" and "magic missile." But other than those and checking a monster statblock in the MM if I'm running a random encounter and didn't have time to prep generic stats, I am generally not minded to open up the book and search for the rules.
I remember in my 4e game a year ago, play stopped for 15 minutes during an encounter because everyone was frantically looking up the rules for whether Power X was able to affect Target Y in an approved fashion. I say this with all affection and respect to my 4e group (they are an awesome bunch and our DM came up with some really interesting and creative ideas) but fuck that noise. To my mind, there are a few options for a GM in such a situation who's seeking to make the game fun and flowing: either make a ruling and have it supersede the rules, or make a ruling and check the book later (the Warhammer solution).
Way I figure...if you think that the rule is really important, then in all likelihood you know it or should know it well enough to fudge it. If it's not all that important, then just make a ruling, go with whatever is coolest or most entertaining, and forge on. I suppose you can look it up if you really, really want to. But you're damn well going to do it afterwards.
In an earlier post of Randall's, he offers this distinction between old-school and new-school gaming:
Let's say there are two major styles of role playing games. From a player point-of-view, the first (and older) style says "Here is the situation. Pretend you are there as your character, what do you want to do?" This style has been superseded over the years with a style that says "Here is the situation. Based on your character's stats, abilities, skills, etc. as listed on his character sheet and your knowledge of the (often many and detailed) rules of the game, what is the best way to use the game mechanics to solve the situation?" Old school play strongly favors the first style and frowns on too much of the second. If your game tends more to the first than to the second, it's leaning "old school." If your game tends more to the second than the first, it's leaning "new school".
I don't say that this is a definitive distinction between the two styles of play, between new-school and old-school gaming. But I think that having to stop and check the rules for 15 minutes (no exaggeration on the time) is a result of the tyranny of the mechanics.
There is a quote attributed to Dave Arneson, which is something to the effect of "The real secret we can't tell DMs is that they don't need any of this," referring to the various DMGs and so forth. I credit PARANOIA with teaching me this - the flow of the game, the story, is maximized when the rules contribute to, rather than define, the setting.
Cast off your chains and be free! You have nothing to lose but your SRDs!