What I find funny is that you apparently created an EnWorld account just to argue about druids wearing metal armor. 74 of your 75 posts to date have been in this thread.
I suppose that's a blessing though as you aren't going on elsewhere about something or other....
Btw, if you're going to keep on about 1e druids? Then I think you should apply your talents to the fact that 1e never codified what exactly was meant by "Metallic armor spoils their magical powers".
Does it mean they just can't cast their spells?
Do they lose their ability to shapeshift?
Can they still pass through overgrown areas freely?
How about IDing animals, plants, & pure water?
These are seriously deep concerns for us 1e players. You should thoroughly examine each one for us and make sure that we've read the rules properly. You know, now that we have this internet thing & all and can properly discuss rules with each other.
Sure, it didn't codify exactly what it meant, but we can get a general guideline through basic deduction. Now since it didn't codify exactly what it meant, there is some room for DM interpretation, just as there is room for DM interpretation on what qualifies as a "chaotic act" or an "evil act" for Paladins, or the DM has to interpret when a Cleric is denied or approved 5th level spells by their deity. The codified guideline is that it has a negative impact on their magic, as per "spoil". To spoil as a verb means to rob something from, or to diminish or destroy the quality or value of. It has some other meanings as a verb, but none of them can actually apply to this sentence, since we're not talking about food, or ballot boxes, or events. It doesn't just say it spoils their spells, but rather their magic, so the DM would simply have to decide which abilities are magical and apply their interpretation of spoil. If they identified animals via magic, then it most certainly would be a spoiled ability, because it's magic, and their magic is spoiled.
The DM would have to codify this either way if there were a Druid at the table, or the party were to capture a Druid. Heck, the party may have Assassins in it and they get a job to capture a Druid alive. An enemy (or player) that captures a Druid and understands that their magic is spoiled by metal armor would likely want to lock metal armor onto that Druid to ensure they don't escape from a cage with their magic, which is an example I pointed out before in this thread. An ideally captured Druid would be like The Man in the Iron Mask, and as per the RAW, this metal armor would impose a penalty on the captured Druid.
The issue with the 5E rule is that there's not even a codified guideline to be used for DM interpretation, unlike what the 5E Paladin has, or the 1E Paladin has, and even the 1E Druid has. There's nothing except they won't do it, which is incorrect as soon as they do it, but there's no listed guidelines for something actually happening if they do. Just like any other class that has taboo, taboo can be violated by player choice. This is the only instance where there's nothing listed as a guideline for when it's violated, intentionally or otherwise, as there's no mechanical implication on the action, nor any explanation as to the taboo itself. As per RAW, if it's violated, it requires a 100% total house rule to impose a penalty.