I think we can all accept that druids in D&D are based on a 1:1 faithful transition of real world druidism. That Larian refuse to implement this is yet more evidence of their idiotic homebrew "rules"
I disagree. I think that the druid class in D&D is a mixture of various mythological influences. It certainly can't be a 1:1 representation of Iron Age druidism because we simply don't have the information available to make any such translation. Nor could it be a faithful representation of neo-druidism - I've yet to see a real-world practitioner turn into an animal or cast a spell.
Like all the classes in D&D (and most other FRPGs), the class is a combination of interpretations of legends, stories, cultural expectation, and game balance.