They're in the business of encouraging users to post content to get more eyeballs and therefore more ad revenue. So commoditising a way of generating a lot more content is in their interests.
This. I recall in their earnings report, they gave a similar answer, I.e the more this technology is made accessible, the better the content put on social media becomes. They also pointed out that any improvements made can be incorporated into their stack like what happened with open compute and PyTorch.