I suspect it might be that the whole mainline Raspberry Pi ecosystem was sort of a hackjob based around "let's repurpose a bunch of bargain-priced Broadcom ARM

I suspect it might be that the whole mainline Raspberry Pi ecosystem was sort of a hackjob based around "let's repurpose a bunch of bargain-priced Broadcom ARM chips". I suspect they had a lot of headwinds with the propriatery GPU. In contrast, if you want to start with toy stuff on x86, at least you can expect the VGA card to be initialized and there's a character buffer at 0xB8000 by the time boot finishes.