Well, last time i checked the best water dispersant was oil-based. Oils
generally make quite good lubricants.
There is also the small matter of "LUBRICATES" writ large upon the tin.
And the fact that if you take a siezed automatic mechanism on....oooooh, say...a Garrard deck, spray it with WD40 and work it a bit, it miraculously frees up and starts moving again.
And the fact that if you spray some down a stiff lock, the key turns much more easily.
I could go on but you probably get the point.......