Project Management knowledge has a value: for firms, that means benefit, i.e., gold.
On the web, one can find lots of knowledge but … most of it is either of no use or not benefit-convertible. Not to speak of disinformation or wrong information.
The web has become a battlefield (you may find examples), therefore the situation has gotten confused, information not so dependable and so on.
In a few words, web-based information is very often unsound or worse; even first-hand information on project management is often not dependable
On the other hand, if you can get real knowledge, benefits are real and gold is always pouring.