I think you might be too optimistic on this one.
Not to mention most of these are probably running with 512Mb to 2GB RAM (G5 iMacs go to 2GB, PowerMacs to 8GB, some go to 16GB)
But more importantly, the point is not the exact quantity of particular models of PowerMac in existence, the point is that if I have one which is otherwise capable of it, this nonsense interferes with me doing it.
And the same goes for every other thing that doesn't fit a mold. What about Linux on a PS3? What if I have a PA-RISC/Itanium/Power/etc Unix workstation? What if I'm using X forwarding so that my "browser" is really running on an UltraSPARC server?
It breaks anything the central planning committee didn't contemplate a priori or can't be bothered to fix. And it's not just old hardware, it's anything new or different. It keeps new platforms from getting off the ground.
If it is then I can't even imagine what its purpose is supposed to be. If my "hardware" is a virtual machine that captures the video output to a file then the blob isn't even doing anything. And if it's not hardware-independent then there are obviously going to be innumerable minority platforms that it doesn't support.