Indeed. I'm pretty sure the issue is that the HDMI Consortium wants some kind of royalty for each device sold with a proper HDMI designation, whereas VESA doesn't care if you sell one device or a million devices with DisplayPort. You owe them nothing extra beyond the initial legal access fee.

Oh yeah, and the burdensome NDA that the HDMI Consortium requires its partners to agree to is another serious problem for the Linux driver.