What's all "proprietary" about Intel graphics exactly?
Their open source support in the Linux kernel is substantially better than AMD's half-assed "sorta kinda open when we feel like it for obsolete parts" approach.
Another thing about this "open" concept that nobody is really talking about amidst the cheerleading: AMD is trying to push *proprietary* AMD-only hardware features that don't fit very well with current APIs -- and that includes Vulkan, BTW, not just the old APIs.
So what are they doing? They are "open sourcing" a relatively thin layer of code that exposes their proprietary GPU features to work *outside* of any cross-platform APIs.
So basically, they open source some relatively low-value shim code for their hardware so that they have an excuse not to make bug fixes since that's been handed over to the community. Meanwhile, the "open source" AMD product is actually encouraging software developers to write code to *non-standard AMD features* that aren't part of any accepted API that would work across platforms.
Just because some code is open sourced doesn't make it a happy "open" cross-platform experience, and there needs to be a little more critical thought applied to this media event.