Except they don't. This is evidence about one potential mechanism. Not evidence saying there are no other potential mechanisms.
This is actually a very common mistake in popular science writing, to confuse the two.
There are eight billion of us, we can’t all be different, there must be at least some categories we can’t be sorted in to, maybe those who find woollen clothing itchy and those who don’t, and those who find blue-light reduction more comfortable and those who don’t.
One of my pet theories is that this hyper fixation on The Ultimate Truth via The Scientific Method is what happens when a society mints PhDs at an absurd rate. We went up with a lot of people who learn more and more about less and less, and a set of people who idolise those people and their output.
Sometimes the causality is clear enough that you don't need sophisticated science to figure it out. Did you know that the only randomized controlled trial on the effectiveness of parachutes at preventing injury and death when jumping out of an airplane found that there is no effect? Given that, do you believe there really is no effect?