apparently in beta it was on the level of melt/vape, but also does AOE damage; I assume they run the numbers at some point and figured it would be too OP, so they nerfed it (just imagine venti with an electrocharged/overload combo). nothing wrong with that since it's better to start low and go from there, especially since you can't nerf stuff people whaled for, but by doing so castrated electro a bit too hard.
even if you could get those melt/vape numbers with aoe, the amount of time and effort it would take in distinct artifacts and team comp is simply not worth it when you can much easier just stack ATK% and ungabunga with pyro, even more when you look at the math and figure EM has much less versatility than ATK (granted I didn't run the numbers since I'm not that much of a theorycrafter, I simply assume their "balance" was based on a certain value).
honestly, once I figured it out it's probably the easiest and fastest of the bosses. sure, you have to knock it off the pillars, but that also means no phases where you have to dodge stuff without being able to interrupt/damage.