Collecting is just one facet of the slot car hobby and maybe more popular than actually racing slot cars. There's a lot of guys nowhere near a slot car track that enjoy collecting the old cars. Only some of us are lucky enough to have a slot car track at home or close by. Lots of guys out there by themselves.
I agree the GRC stuff is not important, rare or a big collector item, but still it is a collector item.
As a type of hobby, collecting old things is probably the largest hobby category in America. Slot cars, big and small, model cars, stamps, coins, jewelry, trains,vinyl records, model airplanes, trains, old hubcaps, guns, starwars, Roy Rogers, plates, books, the list can go on forever!