>>96218612
Because Lovecraft himself was a jibbering nerveless lanklet. His self-inserted response to an IRL existential threat is to melt in place; that's why his monsters seem invincible.

The self-inserted response of his peer Robert Howard, the guy who wrote Conan, is
>fan the ugly mother with the big irons
>shit I'm out of rounds and it's still moving
>where's my woodaxe
>C'MERE YOU
The Innsmouth People, Dunwich Horror and Martin Beach Horror would all have gotten lever-action resolutions. More ethereal types like Erich Zann's monster would have gotten a technological solution like multiple radios playing a vinyl recording of Erich Zann's composition arranged for orchestra.

Difference in author's psychological makeup is the factor.