There are also millions of n=1 studies across the globe, in which parents did the opposite and kids turned out fine anyway.
It's true you can't wait for science. But it's important to realize when something is mostly an arbitrary choice. The anti-tech sentiment that's popular in parenting these days is exactly that - an arbitrary choice without solid foundations.
Perhaps there is a sort of knee-jerk retro-hippie back-to-the-basics trend happening nowadays. But the choice to limit children's exposure to electronic gadgets really isn't arbitrary anywhere I've seen it.
It's more typically reasoned, even painstakingly thought-out choice. One made based on insufficient information, yes, but also with limited time to make the decision.
For example, it is obvious to me from direct observation of my own kids that a box of polished wooden blocks leads to higher-quality play than any of the electronic mainstream crap that they've gotten as gifts: the creative process of building, non-predetermined outcomes, some thinking required, trial-and-error is rewarded, obvious self-satisfaction (and alternatively, frustration), etc.
Likewise, I could provide a litany of reasons why I think spending 30 minutes with a paper coloring or drawing book is an unambiguously better activity for my kids than an unrestricted iPad (which == YouTube, nearly 100% of the time).
An iPad locked to one of the drawing programs — that's pretty different. Once they've mastered crayons and pens on paper, I'll let them do that pretty much as long as they want to.
These decisions might not all have "solid foundations" — perhaps I'm wrong in some of my assumptions. But they also aren't "arbitrary". There is reasoning behind them, even if the reasoning may not be totally correct, and the data is necessarily incomplete.
It's true you can't wait for science. But it's important to realize when something is mostly an arbitrary choice. The anti-tech sentiment that's popular in parenting these days is exactly that - an arbitrary choice without solid foundations.