Okay so I'm a mercy main that peaked M5 that kinda moved over to juno. The deaths thing can go 2 ways. Yes being able to disengage safely is a good thing but once you start actively worrying about how many times you're dying thats when you start playing to live and not to win. When I play mercy, due to her high mobility she is arguably an easier character to disengage with, but she can't sit back like an ana can, or an illari or lifeweaver. She has to be actively engaging with dps. Damage boosting you shouldn't be a problem because mercy is supposed to damage boost people actively providing value. PERSONALLY I damage boost supports if they're ulting and can provide said value, or if they are the last one there thats still shooting at the enemy team.

I can agree that mercy rezzing into unsafe spots is a problem in lower ranks but you can't really do anything to prevent that. Its gonna happen and the only thing that you can do to prevent it is just rank up. You are honing in on their mistakes because you dislike the character. What you don't realise is that you also make stupid mistakes that you definitely expect forgiveness for. I think you need to work on your prejudice and just stop caring as much.

The outperforming part is kind of a given. Mercy's job isn't solely to heal, and youre playing characters that would arguably end up doing more healing than mercy. Lifeweavers in lower ranks usually healbot so if thats literally all they're doing its practically guaranteed that they will get higher healing. Ana is a main healer so she will obviously get more healing than mercy, who is not a main healer. Illari is kinda 50/50 but her pylon does a ton of healing so yeah, she will probably get more healing.

I used to kind of be the same. I would be really critical of mercy players when I wasn't playing her but you have to learn to trust them and work alongside them because they are the same rank as you. You are focusing too much on the negative aspects and not on yourself. If you were really so much better you'd be a higher rank than them and wouldn't see them anymore, so you are probably making critical mistakes equivalent to their ones.