It is hardly surprising that a search would give you contradictory pronouncements, many of them extremely assertive, but generally very poorly informed. For one thing, the evidence is confusing; it is very hard to get controlled results. The same beard on the same face changes from year to year, and sometimes even from day to day. It varies in the number of hairs showing above the skin and in their thickness and hardness.
For example in 1970 a physicist published a suggestion that the rate of beard growth might correlate with male sexual activity. He based this on observations on his own daily yield of stubble during a regular cycle of field work when he was sexually deprived for some weeks at a time.His article met with rather dismissive responses from professional pogonologists who pointed out all sorts of complications. I read the correspondence at the time (I have included references in the Wikipedia article on beards) and while I understood their objections, I did somewhat sympathise with his views and situation. It is perhaps some measure of the changing times not only that at the time he found it expedient to publish it (in Nature, no less) anonymously, but that none of the critics said a word about his sex life or anonymity.
Anyway, the complications included such things as that much apparent beard growth depends on how turgid your facial skin is at the time of shaving. The most logical time to shave is at the end of the day; in the morning your face is swollen from lying down all night. Also, funeral undertakers shave the corpses of men because even if they died clean-shaven, their skin tends to dry out and shrink, exposing stubble. (Vampire fangs are bad enough without the victims having to put up with stubble as well!)
For what it is worth, I never have heard of any non-trivial effect of shaving on beard growth or the texture of beard hairs. I do guarantee that most men's beards grow coarser and stiffer as they shave, but they also grow older, and age definitely produces the same effects without shaving. At the same time, it is very difficult to prove a negative. Although it is sure that snipping off beard bristles without applying any force to them would do nothing to encourage or harm the roots, it seems practically impossible to show that the gentle tugging and massage of shaving would have no effect.
Any volunteers for controlled, double-blind experiments involving shaving only half the face for a decade, then swapping sides? Or zebra-striped shaves?
