There are still a ton of systems which have firmware that does not support large or resizable BAR. Support only became common in the last year or two (after AMD

There are still a ton of systems which have firmware that does not support large or resizable BAR. Support only became common in the last year or two (after AMD marketed as SAM and pushed to get it supported). So requiring the “easy default” to be available means prohibiting any one with a system from ~2020 or earlier from upgrading to these GPUs.