Of course there's a fee.
Do they not realize how expensive it is to fileserve useless videogame data, provide versioning for that, updater systems, workshop storage, curation, promotion etc etc. . . without help?
Is there not a fee for your competing storefront? How would it fund its daily operations?
Right? Steam provides better service and functionality than any other PC storefront. It's ridiculous that there's so much whining about them charging for it. So what if it's a higher percentage? It's also a better service and a large audience. Whoever doesn't like it is free to go elsewhere, unlike console games that can only be sold though the manufacturer's store.