This is the question of a zen master. In four words you've said more than the entire hagiography of TFA. Yes of course, someone has to pay for electricity, but when using an open protocol the user chooses who pays and what they're paying for. If Facebook could go back in time and kill email, they would in a heartbeat. The communications of free people should not be supervised, whether by dictators or by capitalists.
I may host my own email server or I might pay someone to host it. Or the government could host it, or my university could host it. Or I could get it for free by agreeing to be served some ads.
But who pays for it doesn't matter. I can send you an email even if we use very different providers (from the point of view of both technology and payment). For messaging I don't see this yet.
I feel like XMPP was supposed to be the chosen one. I had a google account but chatted to my gmail contacts through my self-hosted jabber server. I wonder if this new generation of messaging apps will get to that point anytime soon.