If found this post on Lobte.rs today and thought it was an excellent piece, so worth sharing.
The writer talks about how the big mail corporations, like Gmail and Office 365, are so popular that they’re centralising an open standard. This can be a problem for a number of reasons, which the OP (Original Poster) talks about.
I won’t go into detail, as I would much prefer you went to his site to read it in detail. I currently host my email with Zoho, but after reading this post I’m seriously thinking about self-hosting my email again.