This is often a very touchy subject for people with differing points of view on the subject. Please take from each response what works for you and leave the rest. We all have different experiences with our disease, different information from which we're working, and different points of view as to what we do and do not want to put into our bodies.
I, personally, have gone through dietary changes (going gluten-free, not eating processed foods, food dyes, etc. etc. etc, eating organic/humane food), homeopathic treatments, massage, acupuncture, and other therapies to try to manage my psoriatic arthritis. While I did see improvements in my health, my disease continued to progress and do irreversible damage. The only medication I'd taken for years was thyroid medication, and I was hoping to avoid taking meds if I could.
I am now on Remicade. The decision to go on a biologic came with reading a lot of (evidence-based) research, discussion with my rheumatologist, and realizing the severity of my disease in my body at the time. Had I gone into remission simply from dietary changes, I would most likely not have opted to take biologics. We know that I've had PsA for many years, and went into remission with each pregnancy (I have five kids), so I am familiar with what remission feels like, and I know that I'm so far from that place that meds are necessary.
In my opinion, if people want to explore dietary changes and/or alternative therapies before going on medication, then they should. All dietary changes associated with reducing inflammation are healthy ones, so no harm is done there. At the very least, the person will learn whether or not these changes are effective in managing their disease. I'd think if the person experienced an increase in symptoms or saw active damage, they would reconsider and discuss drug therapies with their doctor.
As with any diagnosis, there is a learning process that follows. That people are asking questions here about their overall health and nutrition's role in living with psoriatic arthritis is wonderful. I think we all need to keep in mind that how we each treat our disease is a choice, and this is a place for us to share information and experiences and our own choices, not a place to insist that our choice is the right choice for everyone or that everyone should follow the same path toward wellness.