Should Scorpions get buffed?

Coming into DE, there's a multiple of balance changes possible, and I think the Scorpions should be looked over. They're hardly almost ever used with any civ ever. While good against Archers and infantry when massed, they're terrible versus cavalry and get completely flatted by onagers, sniped by trebs and bombard cannons, distracted by rams, useless vs buildings, slow and clumsy so there's not really a civ particularly vulnerable to them. As far as Civs with bonuses, Celts and Ethiopians would rather go Siege Onager in every possible situation, Khmer are the worst civ in the game and even got replacement scorpions and the Chinese again are vulnerable to onagers overall, so not much point in going scorpions either.

Considering every civ with Onagers can just flatten a scorpion army whenever they feel like it, is there a good reason for them being terrible?