If you want the All feed that way, best way I can think of is if you use a client with filters (I use Thunder), try adding the community names to the filter.
I've also requested a "toggle" for filters on Thunder, and may do it myself at some point. But honestly, I switched to my Subscription feed and have been much happier.
Every time a new community has a post that makes Top Day in the first 100, it adds the community to a text file. So I look at that every now and then. I used to have it subscribe my instance, but don't anymore.