There is a lot of confusion out there. Both industrial hemp & marijuana are separate strains of the cannabis plant (hemp is c. sativa and marijuana can be either other strains of c. sativa or c. indica–marijuana has much, much more THC than hemp, which has little-to-none). The site is reviewing only CBD oils made from industrial hemp (more expensive from flower, cheaper & weaker from seeds & stalks) because those are the only kinds of CBD oil one can buy in all 50 states anywhere (not just licensed dispensaries), whether the state allows recreational weed, medical marijuana with an official cannabis ID card, or no marijuana whatsoever for any purpose.
The aforementioned entourage effect is the main reason behind the efficacy of whole plant extracts. There are over 100 ‘identified’ compounds in the cannabis plant. While most of these compounds have their own therapeutic benefit, they combine synergistically to provide a far better performance than any single compound, including CBD. Here are a couple of examples of conditions that benefit from the entourage effect: