I'm curious why you care about whether or not they spent time and effort to write those components themselves. Isn't that their choice as the authors? How does it materially affect you or the product experience? From my vantage point, I love the idea of having even more options as it will create competition, making all sides better for it. Having a singular dominant player in any space (whether it's a browser, kernel, or library) is something we should try to avoid whenever possible.

They can obviously do whatever they want, but realistically, having five different engines that are all 70% complete is not helpful. That's not providing more options. Instead, having one that's 99% complete would be providing more options.

Spreading oneself too thin makes you much less likely to succeed.