Clear skin is the least of the problems with psoriasis. From their website:

    Bimzelx, alone or in combination with methotrexate, is indicated for the treatment of active psoriatic arthritis in adults who have had an inadequate response or who have been intolerant to one or more disease-modifying antirheumatic drugs (DMARDs).

In other words, it's for people with bad cases who don't respond well to other drugs. Keep in mind, other drugs often come with serious complications- constant use of topical steroids will thin your skin, and give you glaucoma if you develop it and use them near your eyes. Many biologics have even worse potential side effects.

On top of that, psoriatic arthritis is degenerative, if you're unlucky enough to get that too, so not treating it means not only constant pain, constant threat of skin infections from scabbing, but permanent joint damage.

I ended up on Taltz, another very expensive biologic, but the eli lily foundation covered almost all of the cost since my insurance wouldn't. Before then, I looked like an alcoholic, because my nose was constantly red and inflamed, and I didn't have anything safe to put on it- glaucoma runs in my family, and I wasn't brave enough to risk anything strong enough.

If that was the only problem, I might not have even gone the route of Taltz, but I was also developing it all over my body, and there wasn't much that was helping.