ES is a great tool. It builds massive meter, is a safe way to end block strings, and leaves your opponent often right in Doomys footsie range, but out of his opponents on block.
Doomys strength doesn't come from damage from ES however.
It comes from the fact that you are afraid to move.
Massive d1 range in footsies
Venom
Anti air grab
Trait
These are the tools that make Doomsday scary. He freezes his opponent because everyone knows "he's got a bar, I need to block this shoulder now". That allows him to do essentially whatever he wants while his opponent looks out for shoulder.
He's impossible to approach because of trait, and d1, and anti air grab.
Sure, ES gets some damage from time to time, but that's not what he's beating his opponents with.
He's beating his opponents by making them afraid to move.