I think you answered the question of "why distribute on the Play store", not the question of "why not distribute on GitHub". Presumably you could do both?
Months in, a new update and Google banned the app forever with no recourse.
You can distribute it but not as you. T&C violation.
We had to create a new app and remove the download.
With this as the explanation: Potentially malicious external APKs within the App.
The App had a link to our website on it's dashboard, our website had a download for all installers (we're cross-platform) and it was the same APK but because of potential for it being malicious, they suspended the app with no recourse. (We did remove the APK download, but couldn't update the App to remove the link to the website)
This was in 2018 and we had been in the store for about a year at that point. It was a patch update that triggered it.