Requiring a user to setup a dummy email account solely for the purpose of sending emails from within other apps is clumsy. Having the same email account setup in two apps is clumsy.
What if I want to exclusively use the Gmail app because I prefer composing my emails in it? After all, it's an email app and that's what it's for.
It's as clumsy as every email link I click online opening Outlook by default on my Windows machine.
As I said, I was speaking practically. Conceptually or theoretically, I suppose you can find some reason to complain. But with the setup I described, you don't have to open the Mail app a single time. And you aren't missing out on any features that I'm aware of.