The differences between these 2 groups are enormous in terms of their play, their attention during lessons, their overall academic achievements.
I will never believe a study telling me that spending 2 hours watching star wars is better for a kid than going to build a fort in the forest.
The kids with screens already built forts and gained that, in this scenario it is the kids without screens that do the same mundane activity over and over while the kids with screens are experiencing new things. You learn the important parts about building forts or dams or tools very quickly, it isn't something you should be doing for years.
One possible reason why that logic might not hold might e.g. simply be that restrictions on screen time might correlate with more involved parents.
There is causality when all the kid can draw involves violence with vague shapes, while others can draw complex sceneries.
Where I do agree is that at the end of the day, the screen is not really the issue, it's what you watch on it.
Without anything else all you have is correlation.
There is no logically sound basis for your argument.
It's staggering to me how many arguments in this thread are devoid of proper application of reasoning.