You are correct. And the example @scottd is the correct way to import RhinoMath in Python 3. It’s not really a discussion of conventions.
RhinoMath is a static class (type) and can not sit directly in front of import because it is not a submodule. IronPython allowed this which is confusing. I’ll check Python 3.12 to make sure this is still the case.
So from Rhino import RhinoMath is ![]()
I created a YT to stop suggesting RhinoMath when completing import Rhino. to avoid the confusion ![]()
RH-81063 Do not suggest static classes on autocompletion

Thanks for reporting this!