I appreciate that there is a body of research discussing possible implications of large-scale phone connectivity, but this does not meet the bar of "objectively

I appreciate that there is a body of research discussing possible implications of large-scale phone connectivity, but this does not meet the bar of "objectively harmful externalities". I'm not even talking about methodologies or replication or evidence or p-hacking (all of which are huge challenges to this sort of research). On a much more fundamental level, the statement "unauthorized smartphone use in a classroom setting is objectively harmful" is a defensible statement. I don't need a study to tell me that, nor should anyone. The extraordinary claim in this case would be the opposite, for which I would have to see tremendous evidence, and which even then I would likely not believe.