When the ban hammer strikes and the dust settles, nothing real will have been achieved (except maybe a Guinness World Record?). People who were cut will find another group to join, or create new accounts to re-subscribe. As user u/ed____________ told Engadget, "It'll be one of those Reddit stunts that everyone will remember for a while (or a few hours)."
If you ask The-Jedi-Apprentice, though, there was a purpose to the ban. "The purpose is to balance out the sub, and of course, to have fun doing it," he said. Since he plays Thanos in the sub, The-Jedi-Apprentice is exempt from the ban, but other moderators are not.
The only other time in recent years that an online community has done something so wondrously pointless was by contributing to Reddit Place. Over three days last April, about a million users made a gloriously garish 16 million-pixel artwork by claiming a tile at a time. Although that was an April Fool's event, it at least led to a hilarious picture that participants could point to as something they helped create, noting the exact spot where they left their marks. Onlookers could observe the many Easter eggs embedded in the massive graphic. People even made socks, placemats and pillowcases featuring it.
The Thanos subreddit ban, however, will leave no such mark, save perhaps for a list of fallen members. All that will be left are the survivors who will have to deal with an emptier forum with fewer people to chat with, and feelings of grief for their departed online friends. But don't be too sad; they want to "die." In an often-depressing world that only gets more depressing when you venture on to Twitter, YouTube comments or the dark recesses of Reddit, acting out this sort of superhero-adjacent fantasy may just be the escape people need.