[davem]

The Hobbit, which has much more essential life in it, was quite independently conceived:

Which is what I said - in origin TH had nothing to do with the Legendarium. Whereas you stated:

davem, I wonder if you'd care to back up some of these assertions that you make with such confidence ("the world of TH is not the world of The Sil", "TH was never written to be part of the Legendarium") with cold hard citations. I'm betting that if you can, I can contradict them with cites that run the other way.

I think what you've actually done is confirm my statement.

But it proved to be the discovery of the completion of the whole, its mode of descent to earth, and merging into 'history'. As the high Legends of the beginning are supposed to look at things through Elvish minds, so the middle tale of the Hobbit takes a virtually human point of view – and the last tale blends them.

I don't think that's how most people read TH. The 'virtually human' point of view is served better by the early chapters of LotR. TH does it much less well. Bilbo - whatever Tolkien says here is much more of a fairytale creature himself in TH. Hobbits only become 'humanised' fully in LotR.

Both are the essential background to The Hobbit and its sequel.

That 'background' is not essential to TH. Did you wonder about Numenor when you first read TH? Did you even know about Numenor? This letter was written to Milton Waldman, who Tolkien was trying to persuade to publish The Sil. Neither FoN or ORP&TA are necessary to an understanding of TH - they are only necessary to an understanding of LotR. TH is not necessary to an understanding of LotR, though.

You may consider Tolkien's integration of TH into the Legendarium clunky or inept and wish that it had never been attempted, but it is demonstrably absurd to contend that it did not happen, or that the world of TH is not the world of LotR and/or The Silmarillion.

Did I 'contend' that - I must have missed myself saying that. The 'world', the millieu, the mood, the tone. The 'world' of TH is only the same 'world' if we limit ourselves to mere 'geography'. A secondary 'world' is not simply a geographical space on map.

"[The Hobbit] is not consciously based on any other book — save one, and that is unpublished: the 'Silmarillion', a history of the Elves, to which frequent allusion is made."
-Letter 25

This statement is directly contradicted by Tolkien himself in Letter 257 which I quoted earlier:

Even so it (TH) could really stand quite apart, except for the references (quite unneccessary, though they give an impression of historical depth) to the Fall of Gondolin

. .

"I am glad you enjoyed 'the Hobbit'. I have in fact been engaged for ten years on writing another (longer) work about the same world and period of history, in which at any rate all can be learned about the Necromancer and the mines of Moria."
-Letter 114

This was written to a schoolboy. Tolkien would not have gone into depth regarding the way TH had become caught up in the Legendarium. By the time Tolkien wrote that letter (1948) TH had become linked in Tolkien's mind with the Legendarium. It was not part of the Legendarium when he wrote it.

Anyway, in short, you have offered no evidence (beyond yours & Tolkien opinion that TH is a vital part of the Legendarium. The Legendarium does not need it & TH is better off without that burden.