Yes ... I think that is true.
https://www.arthritis.org/health-wellness/treatment/treatment-plan/disease-management/the-first-medications-for-psa
"Biologic DMARDs are used if your PsA wasn’t helped with other medicines. If you have severe disease, you may start with a biologic first. The medications are injected at home or given by IV at a clinic. Adalimumab (Humira) is one of the most commonly prescribed for PsA, but there are other choices."

Psoriatic arthritis isn't neglected like some other autoimmune disorders. There are many treatments that are FDA approved for psoriasis and psoriatic arthritis. Most of the treatment options are the same ones that are used for RA.

It is sad that autoimmune disorders like PMR are neglected. The research needed to obtain FDA approval costs a ton of money. It seems the more people who have any given condition --- the more likely the research dollars are spent on those conditions. In other words, the largest share of research dollars goes to those conditions with the largest market.

PMR might be different because people largely want prednisone because of how miraculously it stops the pain. Most rheumatologists realize that long term prednisone treatment comes with many side effects so they don't like to diagnose PMR.

Reactive arthritis isn't very common. It doesn't have any medication that is an FDA approved treatment. Reactive arthritis isn't usually treated with long term prednisone because prednisone doesn't prevent the damage that reactive arthritis causes when it becomes chronic.
https://rarediseases.org/rare-diseases/reactive-arthritis/
Reactive arthritis is called a "close cousin" of RA so it too is treated with the same medications used for RA. Since nothing is an FDA approved treatment for reactive arthritis, everything is considered "experimental" or "off label use" of a medication. Insurance policies usually have a clause that excludes coverage for treatments deemed to be "experimental" especially when the treatment is expensive. They don't care when prednisone is the treatment.

I was lucky to get Actemra approved for use for my diagnosis of PMR. My rheumatologist made the case that I had failed or couldn't tolerate all other alternatives for the treatment of PMR ... most notably methotrexate twice. My rheumatologist further stated that Actemra was FDA approved for GCA so it should work for PMR too. The last criteria was an inability to taper off prednisone and Actemra represented my best chance of ever getting off prednisone.

Humira is FDA approved for uveitis but not reactive arthritis. That was why my ophthalmologist said I should be on Humira. Now my ophthalmologist is saying that Actemra "seems to be working" for me.

It was surprising but Actemra was approved for me for the treatment of PMR. Now Kevzara is FDA approved for PMR. Kevzara will probably corner the market for PMR while Actemra will corner the market for GCA. However, prednisone will probably always be tried first because it is well entrenched as the "only option" for PMR/GCA.

Prednisone treatment costs a lot less than any biologic so insurance companies will want a "documented failure" or significant side effects from prednisone before a biologic is tried.