So is Doomfists but he has to throw himself at the enemy but Widow dose not have to put herself in harms way or put herself at any risk.
And if you miss a shot its no big deal , just take another but with Doomfist if you mess up your dead.
A bad widow who misses shots can still create pressure and help her team to some degree , a bad Doomfist who messes up his combos just dies and when your dead you cant do anything