If you were also publishing those files to the entire world, changing the formatting to suit your site's needs & branding, algorithmically selecting the pieces of media that draw "engagement" and preferentially putting those in front of people, burying others,
and also publishing ads alongside all that, I'd not hesitate a bit to say that
you should be, at least in large part.
Facebook's a magazine publisher at massive scale, that relies on worst-in-class submission and acceptance processes to make money. They're not in the file storage business.