it’s an even more common myth that waxing causes the hair to grow back finer as per your link and all the other sites. it’s just temporary and only lasts as long as you keep waxing. if you stop waxing and let all the hair cycles come up, it will look the same as ever before.
i’ve written lots of times on this topic. waxing and other root removal methods or shaving and bleaching that effect the hair above the surface of the skin - neither have any effect on the follicle to make it weaker/stronger.
EXCEPT in some areas that are sensitive to androgens, in these areas root removal will strengthen the follicle to produce darker and coarser hairs. Examples are upper lip, chin, sideburns, chest.