Reddit mentions of Hair: A Human History

I'll link articles in the bottom of this comment. As a bit of additional info, i've been studying anatomy and physiology along with a short course in dermatology as part of studying physical therapy. I have the danish equivalent of an average A-grade in each of these spanning a year and a half.

Anyways, the (very rough) science of it:
Starting late puberty an onwards throughout adult life, many male bodies will start to produce a hormone called DHT (Dihydrotestosterone). This is basically a "super-testosterone" that increases the growth of hair follicles around the body (facial hair, chest hair, back hair and so on). DHT also has a side effect of narrowing the hair follicles on top of your head, which, along with other hormones, usually leads to stuff like male pattern baldness since the follicles eventually gets starved from nutrition or simply cannot grow anymore. This is also why you'll see a lot of naturally bald young men with amazing beards.

DHT production continues to ramp up through your twenties and even into some people's thirties. This is why you'll see some people's facial hair not really setting in until they're in their mid-thirties. It's also the reason you're able to grow a beard now while not being able to at 21.

Shaving does absolutely nothing to stimulate hair thickness/growth, however it can give the illusion of making your beard thicker as it cuts down the fastest growing hairs, giving the slow growers time to catch up.

Think of it like this - if a woman wanted to look like a man, she could just start shaving her face every day. Since everyone, both men and women, have small fine hair follicles all over their bodies, this would lead to her eventually growing a beard according to your hypothesis. Any certified doctor will never give this advice, instead they will give her testosterone hormones that slowly starts evolving these hair follicles, giving them more thickness and speeding up their growth time.

TL;DR: Shaving does not improve beard thickness or growth. Is just helps keep the hairs at an even length. Hormones are what makes the magic happen.

SOURCES:

https://teens.webmd.com/boys/facial-hair-faq#2

https://www.gentlemansgazette.com/how-to-grow-facial-hair-beards/

https://health.howstuffworks.com/skin-care/men/shaving-tips/does-shaving-make-hair-grow-back-thicker.htm

https://www.toolsofmen.com/does-shaving-make-facial-hair-grow-faster/

https://www.beards.org/beardfaq.php#shaving

https://www.businessinsider.com/does-shaving-cause-hair-grow-thicker-faster-2017-9?r=US&IR=T&IR=T

Unfortunately i couldn't find scientific articles relating specifically to this subject, but this book by Kurt Stenn explains it very well: https://www.amazon.com/Hair-Human-History-Kurt-Stenn/dp/160598955X?tag=bisafetynet2-20

In short, i'm not talking bollocks. Also, you're the one who put out a statement in the first place, it's your job to back up that claim with evidence. Would've been far quicker for you to just google it than to ask for me to disprove that claim.