People used to use this attack in League of Legends a decade ago. If they're losing, they guess someone might have Skype open; and moreover, that their Skype is the same as their summoner name. Then they get an ip address and ddos the entire lobby, causing the game to crash (I think it happened in one of my games maybe once, but I didn't really play ranked other than team ranked).

Also, since all pro & semipro players had each other added, this was possible to do at any time during online tournaments (which was most tournaments - TSM invitational etc). So there were always rules that ddossing was disallowed. But it did happen.

Known ddossers were more hated in the community than known flamers, but a few people who did it "reformed" and went on to be pro players anyway.