Record grading is primarily for collectors who value pressings, etc and often view LPS as investments...hardcore collectors rarely play their collections
This is generally true; but there are 2 types of collectors. I've known audiophiles who are collectors and will only take a record out of its protective jacket and play it on a special occasion, such as a guest who shares the same interest. He will know the market value of every record and keep them in a proper room climate to keep the collection in pristine condition.
Then there is the collector who lives for music and may keep his LPs in bins or milk crates and likes that he has rare or unavailable titles, or every issue of a certain recording. The quality of his stereo system is secondary to acquiring and listening to the music.