It may be worth documenting (we take pull requests for documentation http://appium.io/docs/en/commands/element/find-elements/#selector-strategies).
I would argue that the two use-cases (visually impaired users and Appium element locators) don’t have to contradict each other. You can have content descriptions that help the visually impaired and also be used by Appium to locate elements.
The way I think of it is that Appium is a black-box, automated UI testing tool that is meant to simulate a person using your app. So it kind of makes sense that Appium would locate elements the same way a visually impaired person locates elements.
You are correct though that you it’s bad practice to be adding unneeded content descriptions that are used solely for element location. This issue echoes your concerns: https://github.com/appium/appium/issues/6025