That Harvard blog entry is superficial, not much more than dozens of similar piling-on articles on Buzzfeed and other pop culture magazines. And the WSJ article only confirms what we already know about the FDA -- the agency's mission is to take an extremely cautious position. Lack of evidence about how and why it works is not proof that it doesn't work.
There are many more detailed studies on PubMed and other sites. It'll take awhile to chew through them but few researchers dismiss the claims for relief from pain and anxiety as mere placebo effect. The main specious claim they do dismiss is that cannabis "cures cancer." That claim appears to derive from careless interpretations by laypersons (or clickbait by unscrupulous health gurus) about cannabis being useful for helping restore the appetite in cancer patients, relieving nausea, and enabling them to eat a good diet, which can help with recovery.
And there are studies of the effects on relief from pain and anxiety, but inconclusive. Researchers agree that patients report relief from pain and associated anxiety. But they haven't quite pinned down why cannabis works. And some report that subjects in studies experienced a rapid adaptation to the psychoactive effects of THC, feeling less "high" with repeated use, yet also reported no decrease in pain relief.
One possible risk, not yet definitive, indicates that massive amounts of CBD may be associated with liver damage. IIRC, that's one study.
I'm usually very cautious about supplements, especially those derived from "natural" sources and concentrated as if more than we can get from a normal balanced diet is supposed to be better. I take some supplements, mostly stuff suggested for athletes -- amino acids, etc. -- but always with a dose of salts.
But cannabis has a long history and enough anecdotes about desired effects and unwanted side effects to make it a safe bet. No different from alcohol, the use of which appears to have begun approximately one week after the dawn of man when his week-old fruit fermented. Research mostly added a sciency sheen over what we already knew about booze from thousands of years of experience. On the plus side, science did confirm that tobacco is, in fact, bad pookie and doesn't belong in the human body.