Only partially true on the Pi4: The complete OpenGL stack is now open source using Mesa (it was optional on previous models). Video decoding is slowly moving over from the closed MMAL stack to KMS and V4L2. The boot firmware is still closed though.
Not much worse than a PC then in that regard.
Actually it is.
For example some RPi CPUs have AES acceleration instructions built similar as AES-NI on x86. But due firmware limit we can't use them.
Probably it's licensing and pricing issue...
See the engineer reply in this thread:
https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=2078...
> That is licence for the HW, so you buy it then add the requisite HW to the die, so no, it cannot be added later without redeisgning the HW, which would cost about $1M Plus the licence....
Even if they had been wrong, they shouldn't necessarily have been downvoted, because it still ended up adding to the discussion.