MVP for a sub-theme is simply the .info file? / Clarifications on what's needed for inheritance

[FizCS3]

I was reading this doc to help me create my first sub-theme:
https://docs.backdropcms.org/documentation/creating-sub-themes

I created the file [docroot]/themes/mybasis/mybasis.info with simply these lines:

type = theme
name = MyBasis
description = The default front-end theme for Backdrop CMS, which can make a great base theme.
backdrop = 1.x
base theme = basis
version = BACKDROP_VERSION

When I enable the MyBasis subtheme, it seems to work just fine. I didn't include any style sheets here, yet. That leads me to believe that the above is the minimum viable product for a sub-theme. Of course, further customization to come, but this at least works.

HOWEVER, at the beginning of the doc page's Add your own style section, it says emphatically:

All style sheets defined in the parent theme will be inherited, as long as you declare at least one stylesheet in your sub-theme's .info file. You must declare at least one stylesheet in your sub-theme for any of the parent theme's stylesheets to be inherited.

But, nothing looks out of whack in my sub-theme. Display is the same as the parent, and can change and save the colors via the UI fine...
When I instead use the Devel Subthemer module to help create the subtheme, its UI doesn't make such a big deal about needing stylesheets, and it just casually gives a suggestion of css/custom.css like it is a nice idea but not needed:

Perhaps that section text is outdated?

Also...
At the end of the Override javascript if needed section, it says:

You will also need to create the script.js file; if you simply wish to disable the imported scripts, you can create an empty file.

It doesn't seem like I really need to create this script.js file?

And...
At the end of the doc, it mentions:
"Color.module support within the color directory is not inherited." and "Theme-settings.php are not inherited, unless you copy the settings declarations from the parent theme's .info file." ... but I didn't copy over either one and they seem to have been inherited?