IMC, druids worship the primal forces. A nature God is a humanized embodiment of one or more of those forces. It's an important distinction.
For starters, if I have a druid player I tend to throw in other druids and the like for them to interact with (and get a chance to utilize the druidic language). In addition, much like celestials may be favorably inclined towards a cleric or paladin of similar ethos, fey and other sylvan creatures will be favorably inclined towards a druid by default. However, a druid who wears metal armor won't benefit from that favor. In fact, such people and creatures will be distrustful of a heretical druid by default.
Sure, it won't impact a druid in the same arena as a cleric. It will impact a druid where they would normally shine brightest. The wild and untamed areas of the world.
That's fair. I never assume campaign conditions, and in general discussion only go based on what the rules say as written unless given further context. On that note, I go by the options listed for players in the PHB, which for Druids says:
"Druids revere nature above all, gaining their spells and other magical powers either from the force of nature itself or from a nature deity. Many druids pursue a mystic spirituality of transcendent union with nature rather than devotion to a divine entity, while others serve gods of wild nature, animals, or elemental forces." The latter option here makes it clear that some Druids are simply Clerics that essentially belong to circles as opposed to temples or churches. This rather fits with the idea that they were a subclass of Cleric originally, and if a DM already has allowed such options for the players, that's when it seems to get out of the ordinary that suddenly Fey would hate them for such an arbitrary reason. If I had a party with an Elven Druid, an Elven Nature Cleric, and an Elven Oath of the Ancients Paladin (very possible given that I've been in many campaigns where the party likes to work with a theme), all wrapped in plate and shields, but Dryads come from all over the land to attack the Druid, it would feel quite off-putting.
Now if a DM already rules preemptively that Druids in their campaign can only be the force of nature option and that no Druids gain their power from a nature deity, then I'd be okay with it, although I would still bring up in 5E that it's not against the rules to do so, which it seems you would be understanding of. If they didn't care about that, then fine, as it's ultimately their call. My particular problem though is that most DMs, at least in my experience, don't have the lore of Druids in their world thought out to any such degree, and only have some programmed hatred of Druids possibly wearing metal. For this reason they jump straight to thinking about how to screw over the player if they make the choice, if not outright treating it as an impossible course of action, regardless of what the rules are. Instead of having a world where the Druid has potential consequences, they fabricate a myriad of penalties to target that player simply because they don't like their choice. This is especially problematic to me because it stretches as far as official AL tables, who I feel are not interpreting the rule properly.
Druids seem to be the only ones still getting this treatment on such a large scale at tables playing the latest edition. 5E is made to enable players to add as much flair as they want, and DMs are typically very lenient about them bypassing fluff elements of the general story of their class, but they freak out at the idea of a Druid disregarding a single taboo that has no mechanical implications in the system. I don't see the same DMs upset at Clerics for wielding sharp weapons, but I do see them feeling the need to nerf or remove Druid spells on the basis that they're more powerful than the Cleric alternatives. More powerful spells was a proclaimed intent of their original designs, which was said to be balanced in exchange for their lack of metal armor, so it feels rather hypocritical. Overall people only care about Sage Advice when it hurts Druids, but discard it when it helps them. I don't see anyone upset that Clerics now have access to a wider weapon selection than Druids, which also goes against the original designs, but they flip out at the idea that a Druid may not suffer penalties anymore for wearing the same armor as a Cleric, who may literally get their power from the worship of the exact same deity the Druid worships.
