I agree -- it's what you know, so either you know it/remember it, or you don't. I don't allow "Aid Another" on Knowledge checks, because that doesn't make sense to me. If neither of us can individually remember what Fermat's Last Theorem is, how can two heads be better than one? (I'm not a big believer that committees are smarter than individuals, and I'm an Grognard DM, so I try to do what seems sensible, rather than looking up the chapter and verse of the official rules on stuff like this.)
technically, my memory is more like Google.com. I might not be able to remember something on my own (just like clicking on google.com doesn't bring up an answer by itself). But somebody bringing up informational elements will jog my memory and I can then recall large amounts of detail and facts of a past event or solution.
In short, you babbling about what you DO remember about Fermat's Last Theorem, including sitting behind that blonde chick will then cause me to remember exactly where I sat in class and the session where we learn about Fermat's Last Theorem.
Additionally, in my industry of techno nerds solving problems, we do tend to one-up each other on solutions and information. So one guy saying he doesn't think you can overload a function in C#, will cause another guy to chime in that yes you can, he did it last week, and that it's VB.NET where you can't do that.
In short, the knowledge check dogpile is very akin to real life.
Now how a GM chooses to abjudicate that, whether by allowing one roll and merging it all as Aid Another, or seperate rolls is just an abstraction layer.
I think the real problem ties to ego. I'm a fairly smart guy. I do tend to think of things to ask the GM or strategies to employ that others do not. Therefore, it is a little annoying when I ask about X and fail my knowledge roll because my PC can't be good at everything, that every other player jumps in and eventually gets credit for it because everybody remembers the guy who succeeded and got the answer which required a lucky die roll, not the guy who actually had the brains to figure out what to do.
It's a disconnect of the player ability vs. character ability. Saying "here's an idea, I'll attack with my sword!" isn't particularly rocket science and isn't particularly disconnected from the PC's +5 to-hit with his sword.
Whereas, me thinking to see if I can recognize that small ash pile as to what type of cigarrette it came from so I can match it to the murderer (ala Sherlock Holmes) is fairly clever on the player's part, but not reinforced on my PC's part when he roll's a 1. It further sucks when the next PC roll a 20, and has a better modifier, and then gets all the credit for solving it, when all he really did in game terms is say "me too!"
Smart people aren't usually expecting a ticker tape parade for their ideas, but it is generally annoying to get no recognition for the idea while somebody else gets patted on the back for rolling better on a die.