It is specifically because you got banned for "being under 13" it comes from someone asking a question like "How many candles in this photo?" then you reply "7" then they edit the message to say "How old are you" and voila, underage ban.
What you are overlooking is that Discord is the new MSN Messenger, YIM, etc your friends are not backed up in a meaningful way, nor the servers you're in, if you lose your account, you lose contact with basically your entire internet life and friends.
Discord should not keep those IDs longer than a month at a time once the user is unbanned it should be deleted a week later, or removed from that panel altogether.
I'm not making excuses for companies retaining PII longer than they should. I'm simply stating why someone might give their ID. Another reason is to verify yourself as a bot developer, though supposedly that is usually done via an entirely different third party.
This should be a warning to anyone providing function in any way similar to what Discord is doing. Do not keep PII longer than you legally have to. Don't have to keep it at all? Delete it. Leave a redacted record such as "Image verified by x, removed on x after unban" or something simple if you must. Remove PII from ticketing systems especially on a platform like Discord where users want to be private by design.
The issue then becomes "well why don't they just go back to a Teamspeak server? they can self host it!"
But we're forgetting there that the average person online is not a dev. The most they usually know is how to point and click on something. Which also means they usually don't know how to spin up a Linux machine/VM somewhere and install their own chat server.
Discord is popular because it lets almost anyone on Earth point and click to create a chat "server". If someone can figure out how to do that (eg cPanel), you can absolutely break their moat.
Which is kinda sad. Way back in the mid-2000s, I was playing World of Warcraft with a few people I had met in the game itself. Later on, we chipped in to rent a TeamSpeak server from a company that offered ready-made servers and we had a lot of fun. You didn’t even have to do much admin work. :(
You still don't have to do much these services still exist, even for Mumble. Their limitation is scaling. So if you want way more than just a handful of people, you either start charging everyone an entrance fee, or you cap the server.
Discord's limitation is scaling as well, to be honest. It's incredibly hard to follow a server full of tens of thousands of people. Just because something can scale in a technical sense doesn't mean it will scale in a human one.
What you are overlooking is that Discord is the new MSN Messenger, YIM, etc your friends are not backed up in a meaningful way, nor the servers you're in, if you lose your account, you lose contact with basically your entire internet life and friends.
Discord should not keep those IDs longer than a month at a time once the user is unbanned it should be deleted a week later, or removed from that panel altogether.