When there are several drugs or types of drugs available, doctors usually first prescribe the one with the fewest side effects and/or the one that is least disruptive to the normal functioning of the body. If the less-invasive drug doesn't work, then they switch to other drugs. Those heavily-advertised drugs that are immune-system disruptors and have as their side effects cancer, inflammatory bowel disease, serious infections, etc., and which are administered by injection-- those drugs are much less likely to be prescribed as the first-line treatment than a drug that can be taken orally and has lesser side effects.

I also note that one of those drugs says that it starts working in 4 months. This VERY PRELIMINARY Prurisol study found that it worked within weeks.

Also remember: not only is Prurisol an oral medication rather than administered by injection, but so far the side effect seem to be less. Here's the thing we don't know:

Is this a CURE rather than a treatment? It seemed to be a cure in the mice, but the mice didn't survive long enough after the trial to know whether the psoriasis comes back after awhile.

In any case, a treatment that makes the psoriasis go away for some period of time, which means the person could go off the medication, is certainly preferable to a treatment that requires constant dosing, like Humira and Taltz.