You say doom is too easy to farm, too easy to kill? Doesn’t it go both ways? A doom attacking backlines can get easy support farms, can get easy kills and im talking about his regular combo by the way. The one shot from his is just another thing going for him, doom is also not so easy to kill, he has a ton of mobility and a passive that grants him enough shields to get in and get out. Im not saying doom is OP, I think he’s perfectly balanced where he is. He has his own version of BS kills and abilities.
If your issue is fighting vs a good widow then you have some options, yes genji is one of them, doom can get the job done but you gotta be unpredictable and avoid charging her all out if you know she has a grapple. Ashe can one shot widow, hanzo can one shot widow but you gotta have some skill using hanzo vs a god tier widow, genji gets the job done but struggles as soon as the widow gets a pocket mercy, if all else fails then use a widow yourself.
I agree taking down really good widow players is extremely difficult and frustrating but you gotta work with what you have. I sometimes have a really good time using sombra, I wait for the widow to start aiming and then I put my smg right on her head and she wont have any time to react, the grapple wont even help her especially after widow got her health nerfed. Just get creative, widow is tough to bring down but shes not impossible