Why do people get upset about grouping in comp?

So the only time I play overwatch is when I have 2-3 friends to group up with me. Nearly everyday I get the enemy team saying something along the lines of “lol 4-stacking in QP” and other things of the such. I am just genuinely curious about why so many people get cranky about this. Sorry I have friends to play with I guess?

You hit the nail on the head, anyone who gets mad about that probably does not have friends.

Typically a 4 stack will have more coordination in QP. Which usually means one team ends up getting stomped.

Because lots of the time groups are filled with people who don’t join voice and insta lock DPS