Well, TIL that elected politicians don't appoint judges in the UK and probably most other Common Law countries, so that's pretty cool. Another brick in the wall of my disillusionment with my home country, lol.
Still, in regards to the game rules, stare decisis is a questionable importation, and really does not capture how Crawford operates at all.
Right. DnD rules aren't a legal code. They are guidelines for play written in natural language (which is not casual language), meant to be interpreted by a DM. Sage Advice is there for when someone doesn't get a rule, and needs clarification.
The idea that it's a bad thing for them to change a ruling is just...mind boggling, to me.
Edit: Look at the Sage Advice page linked by someone above. The first answer simply states that the rules for monsters and gear are intentionally generous and in the hands of the DM. Then someone responds with, "Okay that's for monsters, what about animals?" I just....my dude.
Mearls then gives some advice to a different person that amounts to "Sure, why not? Don't get hung up on it."
Then Mearls adresses Wild Shape, reasonably pointing out that WS doesn't specify that you gain the armor proficiencies of your beast form, but that if the animal would have proficiency, you would in wild shape as well. Basically, whether an animal is proficient is loose and up to the DM. Whether you are proficient is also up to the DM, but by RAW would be based on the same DM's ruling on that animal's proficiency with armor. So, if you turn into a wolf, and the DM has allowed wolf friends to be proficient in armor, you are. If the DM hasn't, you aren't. Makes sense.
Digging deeper with subsequent searches, I found Jeremy noting that armor made for a human is, well, made for a human, when asked about magic armor and wild shape. A natural reading of the rules text. To another query, he simply restates that the DM decides whether a nonhumanoid creature can use a given item made for humanoids.
I found some gems where people really struggle to understand the explicitly clear rule that AC calculations don't stack, and one that seemed to forget that Unarmored Defense is specifically 10+dex+wis (wanted the natural armor of a wolf to stack with dex and wis. nope, it's a specific formula)
Most of the things I see him answer on twitter could literally be replaced with "just read the relevant rules text, please." and be effectively the same answer.