This is a common problem (it seems) across social related SE (gaming, workplace, interpersonal etc).
The criteria for an answer require either an objective citation, or that the answer is based on a personal experience, which is described (along with what happened).
That said, very often some answers are called out for failure to provide this, others aren't. Its very inconsistent.
Two quick examples from rpg SE:
- How to stop myself from interrupting the session to correct the DM's mistakes? - top answer doesn't have any relevant criteria. Pure opinion and advice. No problem? Nobody objected.
- Dealing with a Repeatedly Cheating Friend - top answer by axoren doesn't have any relevant criteria. Pure advice and opinion. No problem. No objection. But 2nd answer by GMJoe also pure advice and opinion, is commented as needing a personal reference. Objectively, both are identically lacking cites/personal references.
To be clear, I feel that this requirement to be able to cite a comparable or illuminating experience is low value. Many good answers just won't arise from some specific similar experience, where the same action was appropriate and comparable. Instead users' judgement is a good guide whether a suggested answer is a good fit for the problem. I feel we may lose more good answers than filter/remove bad ones, with that criterion.
So TL;DR two reasons for this question - that the criterion is inconsistently applied, and honestly, I don't think its that good a criterion in the first place.