I have a feeling History Geek was referring specifically to vanilla archers, since I don't think anyone really questions the usefulness of missile units in general. If that is indeed the case, then I would have to agree they're of only limited utility in MTW.

Even setting aside the fact that they're (understandably) horrible in melee, vanilla archers just don't get enough missile kills IMHO. And I'm not talking about their inability to take down heavier units, either (which only makes sense that they can't). Even folks like peasants, militia units, and vanilla spearmen seem to be surprisingly resistant to arrows, despite the fact they're not armoured.

This is one reason I'm looking forward to trying out the next version of The Pocket Mod once it's released, as it will attempt to improve vanilla archers' lethality. Not that I want them to be overpowered, but I've always found it a little ridiculous that they inflict such a relatively low casualty rate, even among lighter, non-armoured units.