This is going nowhere. My answer is the same. Druids will not wear metal armor. No matter how much you repeat your assertion the rule stays the same unless the DM decides to make a house rule.
Except you're the one adding a houserule. The
rules set up a taboo, without any consequence or force. You're adding a houserule that druids physically cannot break that taboo.
If we're going to use "ends justify the means" then we're open up a whole new can of worms. I mean, you can argue that a druid is justified burning a logging camp to the ground if they are despoiling a forest or that the best way to keep a village from growing too large is a good-old-fashioned famine. But you tried arguing there are definitive Good and Evil the other day, so I imagine you can't be trying to justify breaking your moral or ethical codes just for the sake of expediency...
You gotta be aware that differences of scale and intensity exist, right?
Like...You know that pushing someone out of your way isn't the same action as shooting someone, right? This is why the slippery slope is nearly always a fallacy.
The entire premise of the warlock is making a pact with a patron. Huge amounts of text are written on this. Every archetype is based around a different type of patron.
And yet, if a player told me that their warlock has no patron, and instead, in keeping wit the Fey lore I've established in the world and adding to it, has bound fey magic to their will by enacting ancient pacts in ancient places, drawing directly upon the power of The Glade of Twilight's Yearning, and the Bridge of Whispers, and the Halls of Obsidian Night, and is slowing becoming Fey as they use this power and grow in it, I would have clarifying questions and ideas to build on it, but I wouldn't consider it a normal thing to tell them they can't decide what their class mechanics mean in the fiction.
The thing with the druids and metal armor is one little badly-written sentence off to the side.
Absolutely. It's a minor taboo, written as an aside after establishing that Druids are proficient with medium armor.
I think a new player reading the druid description and interpreting it like it's a rule in a board game would come to that conclusion.
I think a new player that was coming to the game thinking about it as a story-telling game where they create a fantasy character, do their best to inhabit that character, and tell a story with other players in a fantasy world, would see that rule and might wonder "why no metal?", or "what the heck happens if they do use a metal shield?", or if there are medium armors not mentioned in the PHB that they could use that might be better than hide... etc etc.
And I mean this seriously. For a lot of people who have been introduced to the game by listening to a podcast or reading popular media or whatever, they might genuinely be more interested in the creative and improvisational and collaborative aspects of the game than they are in a strict adherence to rules that haven't been explained well.
IME a lot of new players come to dnd expecting that the rules won't be treated as particularly binding or important, because they've consumed a lot of dnd media that treats the rules that way. The expect to be able to play a druid that is psychically linked to nature and that is wholly irreligious, or a gnomish druid that is a genius naturalist and apothecary, or a warforged moon druid that is a spirit of nature themself, made manifest in the world in a changeable body of living wood, or a changeling moon druid that has mastered the art of changing form fully into increasingly alien forms, and whose spells are just spells that they have learned, not the gifts of some external force.
And IMO, they are right to expect that sort of freedom.