I've read stories where Lovecraft was a dauntless investigator of the Mythos, risking his neck to bring, and even encode, precious truths for the sake of the human species. I've read stories where Lovecraft was a collaborator. I've read stories where Lovecraft didn't know jack.
But what I haven't read is a story where Lovecraft was as much a myth-maker as the Mythos was real. Where he fabricated truth more than he revealed it, and yet these fabrications were important for more than obscuring the truth.
We speak now of the Great Old Ones being divided into four “elements,” ever since Derleth, and can safely speak of Cthulhu being of the power of the water, and so opposed to Hastur, thanks to that august investigator-fabricator. Because of the investigator-fabricators of the Trap Door Spiders, we have detailed lineages, and uncountable details of their servitors. Many times these things are false, but they are not any less useful. True or not, information has been gained, and any map, however false it may be, makes the territory that much less terrifying. And fear is the greatest weapon which They have. Simply having a name by which to call something can lessen the fear we place in it, and so lessen the power which we give them over us.
But it is more than that. The Great Old Ones rely on being unknowns. They must be darkness. Their natures are that of incarnates; regardless of what they were before, they are now things personified. And ever since 1886, the playing field has changed ever so slightly. The darkness is being explored like never before, and while no more than an inch of the darkness may have been mapped, it is an inch dearly won, and well worth the cost. Once they could flow and shift like water and wear new faces as they pleased. They did not even have names that they could not set aside in favor of other names. But through those few concrete facts which have been discovered, tiny aspects of the Great Old Ones are pinned down, as if now and forever cast in bronze.
Some people complain that the Mythos isn't scary anymore. They say that the world has moved on and left it behind. They ask that if a ship could damage Cthulhu and force him back into his hole, then how much more a nuclear weapon?
And they don't realize: that's the point of it all.