I don't understand this criticism. Would you rather they just prohibited Mojave from running on the cMP?The question to which I can't find an answer though is why on earth Apple decided to release Mojave OS (and officially support cMP), which only supports a metal framework without a proper video card? Yet their recommended video cards are partially crippled? That is beyond my perception of the Apple mindset.
I don't think it's likely they ever modify the cMP to support boot screens on currently available Metal cards. Is there even room in the cMP boot rom to do it if they wanted?
It would make me happy if they simply modified Mojave to allow it to boot with one of the original, non-metal, boot-screen cMP video cards (GT120, HD5770, etc) installed ALONG WITH a metal card so we could swap cables and get a boot screen if it was really needed. That would seem to be a pretty trivial change since Mojave can already boot with one of those old non-metal cards installed by itself. But that almost seems like a bug rather than intentional behavior.