As we can see the current stats of the site:
Alos, we've had similar proposal which all went in vain:
What should be done to maintain a healthy site?
Don't worry! We've passed the private beta mark, while the sites you mentioned were closed during that stage. That indicates that Stack Exchange reviewed our progress and determined that we're doing well enough to continue into public beta, which is where we are now.
Regarding the Area 51 stats: those goals are what you should expect from a site that's about to graduate fully. In days of old, it was expected that graduation would happen at 90 days in or else the site would indeed be closed. Now, sites can stay in beta as long as necessary. For more information, see Graduation, site closure, and a clearer outlook on the health of SE sites.
All that said, we should be promoting this site and growing the community. Asking quality questions and providing great answers is an excellent way to improve the site. We're collecting ideas for site promotion here: How do we promote this site?
Recently we've gone through very critical private stage where 3 attempts since the last 6 years failed to success. See: No AI in Area51.
Since we've successfully passed the final review process, we've now more time to improve and expand our site to match the healthy state, before graduating to full site (it can take months or even years to achieve that stage).
If you check All sites statistics and compare to other sites and take into the account that we've just entered the public beta, so it's not so bad as it looks (>30 sites with less questions asked per day). It just takes time for new people to join and starting using the site, not everybody knows about it yet.
As @Robert mentioned few weeks ago:
we stumbled upon in interesting niche that describes the original premise of this site
Currently we are in stage of clarifying the scope as per: How can we quickly describe our site?
Instead of worrying about it, we should ask ourselves: How do we promote this site?