mdp2020

I did not write anything about "singular they". I wrote against the legitimacy of those linked guidelines, which accidentally include "singular they".

The poster I replied to stated (I remember) that some use of language is made legitimate by some group laying out some guidelines. That some pretty random group («not philologists») lays out guidelines is maybe an "affiliation pass" for their group, but not universally valid.

You need grounds, good grounds. Check those guidelines...

I believe they do. Practice must have a reasonable reference. People are free to contribute to the language - but with some competence.

Certainly. But I referred to the presented guidelines, collectively - not to "singular they". I wrote and intended that _those linked guidelines_ are "not universal".

Could you kindly share a few links that you deem most informative and reliable? Thank you

But it is in such case a strong confirmation about how people are losing conscience of language (not a good thing to sacrifice, in terms of priority - it is very related to thought pollution), and awareness in general, and awareness, attention and quality as values. A progress towards "shallow as a new normal".