-snip-
You made 2 statements. I would have agreed with the first, "it's not a lubricant", a few years ago. WD-40 even had on their label "This is not a lubricant" But now their label says "Lubricates. . . hinges, wheels, rollers, chains, gears"
So either they changed their definition of lubricates-- or changed the recipe.
You other statement "It is not a good lubricant" might be true-- especially in the OP's case where there are products designed for sliding door rollers--- if lubrication is really what they need.
Jim