QUOTE: I have in the past heard PhD professors give bad and wrong information.
I worked for many years in a field situation, where the workers (usually pre-PhDs, graduates and undergraduates) who have 4 or 5 years of experience in on site observations, would moan and groan when a new PhD was assigned to us. It takes a PhD many years of intensive theoretical training and writing to get a degree, but usually he has no practical experience. I would be leary of the advice a PhD gives unless he "dirty fingernails", ie practical experience.
I use cardboard to choke out the viney invasives in my yard. It works. But so far I have to do it every year and sometimes more often, or the invasives will be back. I have also tried wood chips (which I have to buy). They do not work. Also you certainly can plant through wet cardboard. Just punch a hole in it.
