Normal response to undue trauma to the blood supply and tissue on this delicate skin can occur to the hair follicle unit. Scar tissue is a normal response and this scar tissue can block the blood supply that nourishes the hair. The growth of eyebrows depends on the blood supply to the frontal bone area of the forehead. Some people do not have a sufficient blood supply to feed the eyebrow hairs so after a good amount of tweezing over time, these hairs may not ever grow back. Let’s not forget, that thyroid disorders can affect hair growth on the eyebrows as well.
To my knowledge, there is no documented evidence that concludes repeated ripping out of hair from any area can cause hair to grow stronger, HOWEVER…we do understand the responsive nature of the skin. The skin responds to violent ripping out of the hair that is suppose to be its protector. The skin screams and scurries to repair the hair follicle when the hair is ripped out because it is loosing its protector. The skin “knows” when it is injured and reacts by building a stronger hair that cannot be easily removed. We see this when women come to the electrologist complaining that the wax doesn’t work on the thicker hairs anymore. They don’t realize that the body surrounded the hair follicle with scar tissue that hasn’t interfered with the blood supply, and has made it much, much stronger. The opposite can also happen where the scar tissue does interfere with the blood supply, thus hair doesn’t grow anymore.
Not every explanation has a peer reviewed study to back it up, so this is as good as I can explain things. This hair stuff is not always cut and dry, so confusion sets in. I hope you are not confused anymore.