You can do it but it requires a really pedantic and cheesy reading of the rules.
You can indeed only shoot over one friend in base to base contact but the way people work it (that Feanor tried to explain) is that the archer (third rank) shoots over the shoulder of the spearman (2nd rank) but because of the way you have positioned your models the archer's line of sight is not obscured by the front rank. Faenor's diagram explains it pretty well. The archers do indeed have a very narrow arc of fire (straight forward) but that's normally not a problem when the whole enemy army is advancing towards you.
I will say that it's an incredibly cheesy tactic that tends to breed grumpiness during games as whether or not they can see can be quite subjective and is entirely based on exactly where you position your head behind the model.
It's certainly not something my gaming group do and thankfully is not a common tactic at tournaments. I've only ever come up against someone trying to do it once and I must admit I really didn't like it. To my mind it's people taking advantage of the true line-of-sight rule.
Also, anyone who lies their models down for some sort of tactical advantage gets a giant eye-roll from me
I can see why it poses a problem. However, tactics are tactics. If someone tried to spin their troops during the shoot phase I'd call poo poo on their action, but if they have the foresight to make their troops stand sideways (or lay down) in order to gain a line of sight good on them. They've clearly understood sun tzu's proverb of don't attack unless you have a surplus of strength. And that to me, is a clear surplus of strength. I'm not saying it is fair, frankly it's exploiting the rules, but it is a viable RAW tactic.