It *exactly* says why I want to enable use of the non-free by default:

"""
A reason for defaulting to installing non-free firmware *by default*
is accessibility. A blind user running the installer in text-to-speech
mode may need audio firmware loaded to be able to drive the installer
at all. It's going to be very difficult for them to change this. Other
people should be able to drive the system (boot menus, etc.) to *not*
install the non-free firmware packages if desired.
"""
https://lists.debian.org/debian-vote/2022/08/msg00201.html