Countered by most spells, and chances are your opponent will have a spell that isn't just lightning
If you're playing evo pekka and THEN a spell such as log, zap, or arrows your opponent has a lot of elixir to work with (+8 or +9 ) depending on what swarm spell you use. even if your oppenent uses a spell to counter it, no matter what spell they use its a positive elexir trade
i also believe the barbs are criminally underrated, as they can be deadly in certain conditions, but they're not the best. With good enough skill, the larrys are criminal, but they can be countered very easily... i really don't know, most evos can either be countered with a cheaper or equal spell, or they just aren't that good, or they take a lot of time to cycle