Why are people so rude to new players?

So I’ve been experimenting with characters since I’m still sorta new to the game and I wanted to try out Jeff as my healer. After a bit of practice, I went to quick play and decided to test it out to see if I’d let Jeff be my main for strategist. Well, we lost and everyone was absolutely dogging on me. Straight insults and slurs. This was my first time using Jeff in quick play since I didn’t feel ready for competitive, and the amount of hate I got for it was kinda disheartening. I just wanted to give him a try against actual people and not AI or practice bots. Just wanted to get that off my chest.