I don't particularly trust this study; I haven't even read it. I'm just saying that you can't skip studying something just because it seems like common sense.

In the absence of any other study, only if it is safe.

But a non common sense result would lead to more studies, that would either confirm or disprove it. That larger body of studies would very likely be trustworthy.

Sure. A possible outcome could have been: Upper case questions are better

Possible rationale: They get more attention

We need to study such things objectively. Also results may change over time as internet users get used to things