I'd say that your suggested build-up constitutes more stopping-whatever-else-you're-doing than a few turns worth of time-sink. As for killing the scout, people always go on about that as if it were a fait accompli. How do you kill a three-movement unit when you have warriors and slingers, unless you're just lucky enough to have a unit positioned between them and the camp? The scout will get away more likely than not.
The insane geyser of barbarians is something that is problematic to A) higher-difficulty games, because the number/frequency of the eruption is scaled to the difficulty of the game, B) the early game when walls and archers haven't arrived on the scene, and C) when the camp is close to a city. I have a thread you can go look at for a screenshot of what I'm talking about.
Of course, it goes without saying that higher difficulty games should pose greater difficulties, but a high-diff game should still feel strategic, not subject to random whimsy to determine who gets their civilization off the ground and who is bogged down for twenty or so turns just trying to keep their heads above water. Every camp shouldn't spawn three units immediately and then another unit every turn, especially since the actual rate at which camps spawn is also difficulty-based. So, some sort of additional-balancing factor is warranted. For instance, the proximity to a civilization could impact the spawning, with farther camps getting stronger spawns than those just a few tiles from a city. And maybe if they're spawning resource-dependent units, the spawn is tamped down a little as well. That seems sensible to me.
Last night in an Emperor game, I had Germany settling on top of me (we should note that sort of thing is still happening, btw), and a barb camp spawning on top of us went a long way towards handing me their empire. Germany, not willing to wait for archers, declared a surprise war with a retinue of warriors and slingers. Unfortunately, they came southeast rather than southwest and ran smack-dab into the dreaded horsey encampment. They definitely had the numbers on me, so it was a great help to have them chopping each other down. Cologne and Archen fell to sieges by two archers, two warriors, and a scout. Ran off with a warrior and a settler into the ether, the latter of which I eventually picked up as a red unit wandering around another nearby encampment. Ridiculous, really. And for some reason, Germany never did bother to research/build archers. A single one in Achen probably would saved the capital from my mediocre onslaught.