First, I want to make sure my positions are clear. I'm okay with consequences for a druid putting on metal armor, including consequences that are class crippling like a monk wearing armor. I love class identity and don't see classes as just a collection of mechanics. The only things I really have an issue with are the way certain things are written, and the way some people either don't: a) realize that there is an in-play player-agency issue being uniquely, in the entire game, impacted by the druid armor issue, or b) realize it and are okay with it. I don't suppose I can meaningfully convince someone that they
shouldn't be okay with that, but people on this forum are generally pretty reasonable (though we do like to dig in our heels on certain issues) and I believe it is possible to help reasonable people see where an actual issue exists. My primary goal is therefore for everyone (yeah, I'm an idealist) to recognize that there is unique and problematic issue in the social contract (and in setting consistency) arising solely from this one class feature, that has nothing to do with preserving class identity (I don't want druids wearing metal armor in general!) or game balance.
But first, I want to briefly address something no one has brought up regarding the argument
@Yaarel is making that druids lack proficiency in metal armor. Based only on the PHB, this is not as absurd as it appears. Here's what page 45 says:
View attachment 141609
The chart says that their proficiencies are in nonmetal light and medium armor and shields. This is not the same as what page 65 (under the druid class entry) says. While I think the stronger interpretation is to make the class entry primary and say this table is just making a functional summary, that does mean this table is technically incorrect. It is also reasonable to take the interpretation that the table is clarifying the actual mechanical rule, and the entry in the class is including a bit of fluff explaining the reason they mechanically lack proficiency in metal armors. The benefit of the latter interpretation is that neither entry is actually incorrect, they are simply talking about different things.
So, assuming you didn't feel it was too disruptive to your game to allow, and a player was okay with taking the consequences, would I be correct in assuming you'd have them lose all or most class features, either permanently or until they made some sort of atonement? While that might not be my preferred method of dealing with it, I think it's a reasonable way and it doesn't eliminate player agency. "You can choose to do this, but there will be severe consequences" preserves agency. Heck, even "yes, your character can theoretically put on metal armor and suffer massive consquences; but I'm not going to let you as a player have them do that in my game, because I don't like what it does to the game, and if you insist it indicates you are probably not going to be a good fit for this game" is a reasonable position. Those positions, while rather hard line, are fine.
This is also how I see it.
I would like to understand why those who see it differently do so.
For those who don't have an issue based on player agency, could you provide some other examples of player-agency issues that you
would have an issue with? And/or some other examples of restrictions that seem even stronger than the druid armor one that you would also
not have a problem with? I'm trying to figure out if there is a general lack of compatibility on perception of player agency issues, or if the issue is being viewed differently by different people.
For instance, if you want to preserve class identity, and prefer druids don't wear metal armor, I'm on your side. No need to fight me. If you think there might be a balance issue, I'm not strongly attached to any view. Again, not your opponent on that. If you're just trying to make it clear what the rules are in the book, I agree that the stronger reading is that "will not" is a rule. What I want to get at is how you feel about the player-agency issue
in isolation from every other issue.
I think it has been explained fairly well why many of us see it as a problem. It does something nothing else in the entire game does--it prevents us from making a choice to violate a character's initial beliefs during the game and face the consequences (whatever those might be). This doesn't make any sense from a religious perspective. Even the most devout religious people violate their beliefs on occasion due to human imperfections, regardless of how much effort they put into not doing so. Many people change religious beliefs. In D&D, angels can fall and fiends can rise. It seems odd to say that members of the druidic faith (or character class) are
literally incapable of choosing to change their beliefs or give in to temptations to violate them. I'm sure it was correct at one point to say that a fallen D&D angel "would not" do evil acts, and that a risen fiend "would not" do good acts. But they changed over time. How are druids different?