That said, Twitter is no longer "open" like it used to be - I bet it just won't handle the public traffic anymore. That is directly tied to cratering revenue but it's hard to untangle from the owner's self-destructive drug-induced behavior.
It's a testament to the quality of the codebase in general. Good code is hard to kill, but it WILL be eroded to the point where it can no longer grow and be better.