Check the TOS, many companies don't allow accounts to be traded and will ban the account. They have bots that will detect a change of user. My son recently returned to a game he hadn't played in ages. Started off badly but, within a game, he remembered what to do etc and was playing well. His "improvement" was a problem. It's likely that the person who buys the account will have a different skill level and that will be detected.
I guess that gamers are not the most motivated people, but a gaming company that takes steps to prevent the fair sale of its product on a secondary market could be open to a massive class action lawsuit and/or action by the Federal Trade Commission here in the U.S.
Yes, but it takes a bit more than firing off a nasty tweet or meme in a fit of adolescent pique. You actually have to get off the couch in Mommy's basement.