Neither did Mastodon.social or Mastodon.online, though honestly I’d recommend people steer clear of those instances when signing up for a different reason, they’re also very widely blocked or limited by a lot of servers due to issues with spam and moderation. Ironic that these instances are already too big to effectively moderate, yet threads is bigger and also way worse (see link in other comment about their moderation issues) and yet people still want to federate with them.