Agreed. Wouldn't mind to subscribe on all 3 and get posts to my feed.
Additionally, Lemmy and Kbin are being actively developed, maybe this new wave of people pushes them to create tools so that you can combine magazines and communities into one metafeed/community where you see all the posts to all three communities.
Honestly, the one with best moderators that put effort into building and maintaining a community rather than letting it sit there. Building a space like this isn't really luck as much as hard work. Take a look at [email protected] for example, they are promoting the community on the subreddit and being (pro)active on their instance, and it's working. If we make it a nice place to be people will come, but it rarely happens on its own (especially with reddit looming over as established competition).