AMD has actually gone out of their way to embrace open source and the Linux community.
Not really. They've trickled out just enough information to support new cards, while never really providing enough information to use old cards. My R690M still doesn't work properly under Linux.
Much of the bias against AMD is left over from ATI's disastrous drivers (even proprietary) back in the day.
No, most of the bias against AMD is due to their disastrous drivers today. I've still never had ATI graphics work properly with ATI's driver. If there's not a hacked driver (e.g. DnA) available, then the driver causes me nightmares and headaches. CCC is still festering shit. It's as big as a driver should be by itself.
In fact, the release of AMDGPU and in fact their entire unified driver plan leads to more openness.
So far, what it hasn't led to is their hardware working properly, which is a lot more important to most of us.
AMD is far from perfect, but they do seem to be interested in making FLOSS a part of their future
Nah, it's mostly lip service. They abandon hardware from their driver long before it's properly supported, nVidia supports much older hardware in their driver. And they don't really give all the information you need, just little dribs and drabs.
Maybe someday they will deserve your admiration, but right now, they're fakers. Maybe someday they will e.g. provide the support for Linux to do proper power management of mobile Athlon 64 processors.