> Automated testing is not impossible, it is just harder.
How one can automatically test that, for example, on a random laptop sound works or the video has proper white balance or the laptop can pair with a random bluetooth device in various supported bluetooth applications? Or one can install on a server with some strange BIOS quirks?
In those cases it is best to ask the user. But for that one needs easy to use infrastructure to try new things without breaking stuff that currently works. Plus one has to listen to the feedback. Without these things one simply would not get enough test data for the rapid release.
> Debian testing is a good example of how to do things.
Debian testing works if one releases every couple of years at best. For rapid releases one has to do much better.