As an editor of a couple of publications, who also hunts for fun content to share, I agree with you on many of your points above.
Those with an audience off the platform (or a huge following within it) certainly don’t fall under this pitfall.
And anyone who wants to build a personal publication on their own are absolutely open to do so, but as you say they are inadvertently limiting their discoverability. (I have a “project publication” myself, because it just makes sense to keep those weekly posts in one place where I can control the look, but my numbers show that I certainly lose out on the wider following it could potentially have elsewhere.)
The lack of profile personalization is undeniably a major point brought up over and over — but one that would certainly solve a lot of this problem.
Just imagine if you could share your content to your own followers in the new wonderful layout options available to pubs AND still be able to submit your work to publications so their audiences could enjoy it!
A better way to search for publications (a collection maybe? or a directory of sorts) would also perhaps alleviate some of this disadvantage. There are SO many of these personal pubs that are long extant but still listed in search results.
Thanks for opening the floor for this conversation! I’m eager to discover what Medium will bring forth in the coming months.