Well, yeah, but that's like saying that producing a tree of pomaceous fruit hides the fact that citrus fruits exist.

(Yes, I did make an apples and oranges joke.)

The tree appearance just makes it too inviting to imagine PIE as some pristine ur-language, the kind of original language of Babel. I'm not saying that people explicitly think these thoughts, just that it's easy to get this impression, even if it's not conscious. The fascination about the original human tongue in Eden used to be a common intellectual preoccupation. My point here is that PIE is quite a different story.