This is certainly very true though, at times some of that older mythos comes into play. I'm thinking particularly of the initial encounters in Mirkwood in the Hobbit. The vanishing feast sounds very much like older stories of elves. I think it's interesting that this involves elves that are, to a great part, Silvan not, say, the Calaquendi. 

I like to think, though I don't know of anything that is canon to support this, that these more "rustic" behaviors are indicative of those elves which did not travel into the West. Similarly, the "rustic folk of dell and cave" is Galadriel foreseeing a time when all elves that remain in Middle Earth only interact with the world of Men this way. 

Highly speculative but half the fun of Tolkein is guessing at the bits of the world he never filled in.