Hello, Giving a general answer first.
First, only reported issues can be fixed. Then, when an issue is reported very late in the release process it's really difficult to fix it, or stop the release because of it. We cannot halt the world just because on some hardware there are driver issues. It happens that for the reports that were received, I couldn't reproduce them. I'm afraid I don't have a cristal ball, so I cannot fix bugs that I cannot reproduce. That is why we need testing as early as possible, to have the time to iterate over the discovered issues. Alpha versions of the Debian installer were released one after the other in the past coupe of years, and the debian-boot team took care of notifying debian-accessibility, *precisely* to have people test them early, so that issues can be detected early enough to be able to fix them. Samuel