Instead of mentioning your instance so we can help you you seem to have other motives.
Edit: but if you want the logic. We had discussions internally as well as with other instance admins about this and the conclusion was - even from other instance admins - that closing registrations would be a bad idea. Currently a lot of people are sent to lemmy.world from reddit and 3rd party apps for example. If people land here and are not able to register they might not look into it further and give up because it is too complicated or overwhelming. So that would actually be worse for the fediverse. That is why we want to make the sign up page more informative and provide options.