These are 4 different companies that compete with each other (Google Cloud vs. AWS and Facebook vs. Twitter, also although you didn't list it Apple vs. Google) in the spaces relevant to this conversation (cloud services, social media, and phone apps).
One can always list all the players in an industry and call that set "a monopoly and should be broken up". Or we can just take this for what it is, which is that some entity is so toxic that none of these companies (which compete with each other otherwise) want to touch it.
Google has monopoly on search, Amazon on online retail and to a lesser extent cloud hosting, Facebook on social media. Twitter on 140 character word dumps so that's maybe not at the same level bad as the others. Edit: Apple doesn't really have a monopoly on anything.
One can always list all the players in an industry and call that set "a monopoly and should be broken up". Or we can just take this for what it is, which is that some entity is so toxic that none of these companies (which compete with each other otherwise) want to touch it.