I find it ridiculous. I've had psoriasis for about 40 years. Flare ups come and go with no predictability. Some say stress, others say weather, blah blah blah. The only medical treatment I have found to be effective over any length of time is the biologics. Humira works very well. I have used methotrexate, all the creams, lotions salves, coal tars, light boxes and steroids with little to no effect. Methotrexate works, but with side effects, and it returns when usage stops.
If a sugar pill had 20% effectiveness, doughnuts and coca cola would work. I've got my fingers crossed for Prurisol. It's the reason I invested in the first place.