There is no one proposing that non-free should be mandatory. The original topic was whether it should be possible to install Debian at all, noting that there are situations where this now is so difficult that it will be percevied as "impossible" by some users.
I believe it is an undisputed fact that there are computers which need non-free firmware to access the Internet. There is most likely also a group of potentional Debian users who would prefer to use WiFi for installation even if they have other options. Should computers/users with WiFi-only Internet access be supported by Debian? I'll assume the answer is yes. After all, Debian is "The universal operating system". It has been documented in this thread it is possible to install Debian on such systems. But the images which allow this without additional steps is well hidden. And the procedure supported the default images is so complicated that even expert longtime Debian users have a hard time using it. The procedure would obviously be simpler if the firmware was included in the default installation image. I don't think there is any dispute so far? So we have established an upside. The dispute seems to be about the downside. Is there one? The firmware we are discussing is avaliable to every Debian user with Internet access. Whether it is in the installation image or not does not change that. Availabilty does not imply that the firmware must be used. The installer can still ask about using "additional non-free drivers" for installation. The difference is that the user will have an actual choice. As mentioned before, the use of non-free for the installed system does not depend on this at all. And IMHO, it should be left as an unrelated question. Even allowing temporary usage of non-free firmware to install Debian on a system with only free software. No choice is taken from the user. What we are left with is users who are offended by the mere existence of non-free binaries on a Debian image, and who see this as significantly worse than the non-free firmware in their NIC, SSD, EC, CPU etc. And worse than the existence of the same firmware on the Internet, including any Debian morror serving non-free. These users, if any, could be served by a non-default Debian image where the non-free firmware has been removed. Does that downside even compare to the upside? Are there any users who are offended by the mere existence of a file in an installation image they are free to avoid? Did I miss something? Debian is "The universal operating system". The implications are clear in my opinion. Bjørn