I totally agree. My articles have benefitted from publication initially inside larger publications, but I also like to have them in my own collections.
I have been thinking about curating my medium posts outside of Medium and then linking to the external collections from an article in Medium. I have other reasons, but one of them is that I would then be able to submit articles it to publications run by other people.
Or, instead of multiple publications, maybe content owners could generate a collection based on the content’s tags. This would free them up to contribute to others’ publications.