You're completely right, it seems a little counterintuitive but one thing I learned early on while building a different community site (Designer News) was the way to build a wholesome community was to be invite only in the beginning. That and real first and last names.

Which means it's a poor user experience. Sorry for the trouble, I wonder if any folks have better ideas here?

Not a single page even mentions that it's invite only =/. Context for that would be a good start heh

An invite only for designers because the barrier to entry is so low it makes sense.

Not sure that would work or is as helpful in this case. The community seems more friendly than most and the general goals of many are to learn something new, powerful and fun. If you build a community around those themes I think it will attract the right crowd.