The convention on desktop and mobile is not to have a submission at all. If you click one of these "mercury" buttons, you can always have up-to-date state.
Forms and submissions are mostly a web convention. I too think that's more natural, but there are a lot of existing contexts like settings where the expectation is that making the selection doesn't require an explicit "save" step.
Forms and submissions are mostly a web convention. I too think that's more natural, but there are a lot of existing contexts like settings where the expectation is that making the selection doesn't require an explicit "save" step.