Netflix has a large catalog, but most of it is either crap or owned by other studios and networks. They are all taking their content back to start their own service.
But Disney seems to have all the franchises that everyone wants to see. Add to that the major broadcasters are also pulling content, it's not just Disney. NBC, ABC, CBS are all pulling their content from Netflix and creating their own Disney+-like competitors to Netflix. HBO never even put it on there (they have had HBO Go for a while).