It seems like the simplest approach for Twitter to make would be to remove specific posts, rather than accounts, for tweets made over a year ago (say). It's not

It seems like the simplest approach for Twitter to make would be to remove specific posts, rather than accounts, for tweets made over a year ago (say). It's not fair to hold someone to account for the actions of a very different person, even if they happen to be a continuation of that person. (Edit: And to be clear, I would have been a-okay with Twitter having banned the user at the time, for the content in question!)