While I agree on every community needing at least a little content, I'm not sure I agree on the second point: if this place had a lot more communities, even with two active people each, it would also attract more users, or at least it would make me visit the site more and would have reduced the time I spent indecisive on signing up.
A community isn't just a bunch of content but also a possibility for it. It's the reassurance that there is at least another person on this site who shares your interest. It's somerhing that makes it more attractive not to jump from site to site for each different interest. Those who create them are doing their part by being available as moderators, which is already something that should not be taken for granted.
I have plenty of ridiculously niche communities I'd like to see that would be lucky to get 3 members each, from lichens to cron diet (longevity diet with a little less calories than mantainance and very micronutrient dense) and scientific (or just fanboy like and excited sometimes, waterhomies style) discussion of nutraceuticals (such as garlic and ginger and turmeric) and of mitochondria and of microbiome, to specific anime/manga fans, to animal movements (crawling in various ways as a sport), and I could go on, but I don't create them because I don't want to mod them since my relationship with tech makes me go through unpredictable offline phases