The entire social engineering of sending everything off to 3rd party is something that really irks me. The touted convenience of faster to deploy updates by using 3rd party rather than depending on local version updates has never been enough for me. It also was the sugar pill for switching to rent seeking SaaS to gain traction.
I don't want my web server dependent on anyone else's server/service being available or in any other way slowing down my user's experience.
The only service that I have no local solution is payment processing.