If a company is prepared to put their balls on the chopping block over this, if that company has millions of dollars at stake over this, if that company has a priority of a working program that runs well rather than taking sides in a religious war - I’m inclined to believe them.
Fair enough, so let’s analyze this on those grounds.
NVIDIA does indeed have “millions of dollars at stake over this”. But what exactly is “this”? They’re basically saying, “Don’t use the standard method; use our proprietary extension.” Or put another way, “Don’t use the standard method; make your code only work on our hardware.”
How does NVIDIA not have a stake in “taking sides in a religious war?” NVIDIA has financial reasons to want people to use their proprietary extensions, and financial reasons to encourage people to not use similar core functionality. With AMD being less competitive and having financial troubles… why should we expect what NVIDIA says to be on the level here?
What would NVIDIA have to gain by putting effort into making VAOs more performant? The more they push their proprietary extensions, the more people buy into it. Which puts people in their ecosystem. This puts pressure on some developers, who then start wanting their customers to buy NVIDIA because that’s what they write their code for. Thus pushing sales of NVIDIA hardware. Which in turn increases NVIDIA’s marketshare, thus encouraging other developers to make the switch, which causes more sales, etc.
NVIDIA doesn’t make more money by having fast VAO code. NVIDIA makes more money by encouranging more people to write NVIDIA-GL code instead of OpenGL code. Does this mean that they have convinced their developers not to work on VAO performance? Well, someone told them to write the bindless graphics extensions to begin with. Whether that someone was on the driver team, pushing for a performance extension, or was someone in marketing wanting to differentiate their performance from others, I can’t say.
But you cannot reject the very real possibility that they’re not on the level here. I see no reason to blindly trust an organization who has a direct financial stake in getting people to not use cross-platform OpenGL code.
There’s no way to know for certain because NVIDIA guards their hardware specifications vigorously. We only have the word of someone who has plenty of reasons to lie.