So long as you can get "scouted" before you can possibly produce units to intercept the scout, barbarians in the opening 20 turns are and will remain putrid design. That's not the kind of resource/expansion constraint variance on solely RNG a sensible designer puts in a strategy game. After that, they're reasonable. You invest to stop them of don't and risk paying for it. In those opening turns, however, nope. If your opening build is slingers to intercept scouting it should at least be possible to do so.