I think the problem is that this stack's approach to Back It Up is at odds with the broad SE philosophy of providing expert answers. Experts are often called on to give opinions on situations which they haven't seen an exact analogue of before, and which are not easily traceable to documentation. Those answers can't just be oracular; they still have to be supportable, but they can often be based on judgement and general experience.

Here's a great example: aviation.stackexchange.com/questions/21082/…

There is certainly no reference for "why do VTOL have only one engine?" and the accepted answer has no "in my experience..." disclaimer. Nonetheless, it is a complete and supported (and falsifiable!) answer.

@fectin What specific questions are requiring Back It Up! that should not be?

So far no one's bothering to define that and just handwaving, so it's not super actionable. Some questions obviously need support. Back It Up! does not require personal experience - it requires that or something citable (as that aviation answer has). But if you're just making something up, then it needs at least experience.