It's not about the uptime or scalability. Everyone has to make the choice for themselves if they value their time less than $12/year (Or free if Google is an option) for a critical part of their digital infrastructure to set all these moving parts up and keep them running over years.

I'll stick to Fastmail, where if something isn't working as expected I can just email them and get a response from a real human.

It doesn't change the fact that the workflow gp explains is a duct taped construct.

It's hyperscalable and highly available today, until the API changes.

Yeah it's highly available until it isn't and then that turns into your problem rather than something like Gmail just working