It took a few days for instances to be upgraded and admins to fill in their profiles but it's looking much healthier now!
An instance with 3 or more topics is newbie friendly. Topics are bundles of communities that are shown to new accounts during their initial on-boarding and by choosing some topics they automatically join all the communities in those topics.
I'm finding that pretty much every instance has 3 or more so this filter is not so useful, except to exclude development and testing instances. I'm not sure where we'll end up on that.