Agree, but it’s important to point out that .gg grew popular in the gaming crowd because “gg” in gaming means “good game”. It’s used in-game in the chat by many players of online multiplayer games as a way of thanking each other after a match. It can be used sincerely or it can also be used sarcastically but in the latter case you’d typically say “ggez” as a taunt implying that the win was easy (“ez”) because you are more skilled than your opposing team.

And for .io of course that one is/was popular among tech companies because it looks similar to “I/O” (input/output).

.gg means "good game" so I can see why Discord would use it.