Developers don't want to create seperate Apple only backends for everything. Users want to use software, they don't care about what backend is used. When Apple has to personally implement a metal backend for blender, it's obvious that there is a problem. This is despite blender being one of the most well-funded open source projects. Having to support multiple backends also increases development time and future tech-debt surface area. It's mostly not a moral arguemt as you seem to imply. This is just a feature that developers and users want. Apple is free to not implement it. It just means that many apps will not support Apple, or they will support it at the cost of other features, or they will use MoltenVK.