In the case of Gmail vs. Fastmail I’m not so sure it’s a downgrade, but if you switch away from Google Docs etc. you will indeed lose things you were used to (great collaboration, speed etc.)

However you also gain something. For me personally actually three things:

* I no longer feel like the service I’m using is like a rug that can be pulled from under my feet at any moment

* My data (mail, documents, etc.) are now actually under my control and not in some “arbitrary“ format on a server I can’t reach except from my browser

* As a bonus feature, my mail is only read by me and my behavior is tracked by no one