Jumping in here because I’m picking up on perhaps a little bit of a knowledge gap that’s making discussion more difficult than it needs to be.
When @kylegospo is providing the 2/3s number, he is referring to users of the -deck image variants (which make up roughly 2/3s of image pulls).
These are not typical desktop images - they do not boot into a traditional desktop environment, like KDE or GNOME.
Instead, they boot directly into Steam’s “Gaming Mode” environment, which is built on the gamescope compositor (a barebone compositor specially developed by Valve). This provides a tenfoot/console-like interface, as follows:
These images are intended to be a drop-in replacement for Steam Deck OS for handheld console-like gaming PCs like the Steam Deck (Lenovo Legion Go, ASUS ROG Ally, MSI Claw, and other hardware in the same space).
These are also to be used to create gaming theater PCs, for streamlined use on a living room television.
The issue with “just using Flatpak or a container” is that the gamescope compositor simply does not work in those situations, when paired with Steam’s Gaming Mode, as it has the same concerns as a desktop environment. There would simply be no way to serve Gaming Mode as an environment.
As such, moving to this would essentially force Bazzite, as a project, to abandon its primary reason for existing - alienating 2/3s of their userbase. The remaining 1/3s would be served a lesser experience for a variety of more paper cut reasons, and VR is already a complex topic which would get even worse.
Alongside the reasons that were elaborated on above with regards to Proton (no way, without polluting Steam configuration files that Bazzite shouldn’t be touching, to provide the streamlined experience which is the intent of Bazzite), this is one of the main points of contention with this proposal as it stands. It may be emotionally charged, but it stems from a completely practically-driven usecase concern.