That's incorrect. WD-40's website says that it is a lubricant and can be used as one. It was originally designed as a water displacer by combining several lubricants and adding volatiles to help penetration.

It has some downsides as a lubricant - the volatiles make it thin so it's not a very long-lasting lubricant. And the soil removers in it tend to create black streaks after some time. But it's still a fine short-term lubricant for many things. It's poor for garage doors because you want something long lasting, so I would agree with your recommendations, but wanted to correct the info on WD-40.