Blue light has a documented effect on our circadian rhythm and melatonin production. It’s been studied quite a bit. I’m sure mental overstimulation is a component, but it absolutely is not the whole story.

In Western society, there is a big focus on silver bullet solutions because people don’t want to address issues in a holistic way. Thus, you have blue light filters instead of turning the screen off.

Of course a 6" screen doesn’t produce as much as a ball of nuclear fire

But that ball of fire isn’t 12 inches from your face at midnight. And, the majority of blue light filter use is targeting sleep quality. A good portion of this comes down to cumulative exposure time. The best solution is to just not look at screens after a certain hour, but no one wants to do that.