Why is it acceptable...

Why is it acceptable for Diamond players to queue into bronze/silver on smurfs then tell you to kill yourself when they point out something they did badly on?

They were Nidalee who constantly faceplanted their leaps and missed spears, all I said was it was sad we won so hard even with the bad mechanics Nid. This was before I knew they were a Diamond smurf.

EDIT: Anyone new who happens to be confused by the story I'll try to recap the entire thing here. Nid missed a good amount of their spears and pounced into walls quite often instead of going over. She still ended the game 21/3/5. I commented on how sad it was that she messed up a lot of the Nidalee mechanics yet she still carried us so hard. Afterwards she tells me to kill myself and that she would add me on her main. Nidalee leaves the post game lobby, my botlane (Who actually were bad and ended with a combined score of 3/11) also tell me I'm trash and that I need to go die and that the only reason I won is because of Nidalee. I agree that I didn't do well but say they did worse. Nidalee adds me on her main and is still ranting at me telling me I need to check my own problems before telling someone else they did badly. At this point I'm confused over how insanely toxic they're being just by saying she carried hard even after messing up. After talking for a minute Nidalee says "idk man I'm high and it's early morning" but keeps acting as if they're the perfect Nidalee player and actually saying they are #1 Nidalee on NA. I ask them what I need to improve on, since they're Diamond and I'm sitting in Silver they should probably know, they only say "whatever man I'm blocking you. Bye" then go offline.

P.S. My end score was 7/5/12 on Aatrox against Cho'Gath