In the online gaming space, Skype used to be a big enabler of DDoS attacks due to its P2P nature. Almost everyone used Skype back before we had Discord and other alternatives, and there were plenty of sites that you could paste in someone's name and have their IP in seconds. Even if they weren't online, Skype servers cached a bunch of previously seen IPs. Then they would paste that into a $5/mo "stress test" tool and the victim gets a short DDoS (1-5 minutes) but enough to disrupt / kick them out of the game.