Originally Posted by
kimconyc
Prevents corrosion between metal-metal contact. Keeps moisture out between metal-metal area (this might not apply for people riding in either dry areas or fair-weather riders).
As to the second part your statement, this is not true--for example, people using SRAM Red cassettes.
Later.
ah, good old one-piece red cassettes.
all my FHB splines and lockring threads are covered in some mixture of chain lube and grease.