Do you have a source for your claim?

Lack of known good reasons, and their major infamy in perpetuating lock-in in general. They have only themselves to blame for being seen in negative light in this topic by default.

That doesn't mean their isn't good reason. I guess they believe they can build a better product by having control over the graphics pipeline. Obviously I cannot say for sure what they think in that regard, but neither can you.

Not very convincing. They often used excuses of good reasons to do sinister stuff, so, they'd need to work much harder to fix their ruined reputation.