The thing is we're not medically trained people, just patients with psoriatic arthritis who are willing to share our experience. A lot of people here have shared their experience, as well as what knowledge we do have, with you. Before starting treatment I trawled forums and other sources of information and gleaned what I could from that.
Perhaps it was easier for me to make the decision to start treatment seeing as I felt like death warmed up. There was no way I could continue like that. However, the experience I'm sharing now is that when that first, long, dire flare-up hit me, I looked back and the undiagnosed symptoms I'd had for years started to fall into place. I'd say they became gradually more debilitating systemically - all of me was affected in addition to the increasingly severe joint stiffness and pain and the disabling effects of that. I don't think you've mentioned how you feel 'in yourself'. Are you aware of intermittent or creeping fatigue, feeling very much 'under par' at times, any chills or fevers etc.? If not, that's great but if you decide not to start treatment then it might be as well to keep awareness of those warning signs at the back of your mind.
When Seenie mentions 'symptomatic relief' I'd imagine she's referring to these other PsA symptoms and indeed to the joint pain and stiffness that often dogs many of us. There's also a little something called enthesitis - inflammation of the points at which tendons join bone - which can be very painful. DMARDs can provide varying degrees of relief for these symptoms. Myself, I found that Mtx (my first DMARD) eased up my extremely stiff knees to the point at which I could walk again and also allowed me to use my left arm which had pretty much seized up. And the effect built up over time until I was actually walking normally & quite happily. By the time I started biologics, 2 years after diagnosis, I felt like a relatively healthy and active person again. It took me that long to find a good rheumatologist and the folk here supported me in that. He immediately said that I'd need biologics - and this addresses your point directly I think - because the continued swelling put me at ongoing risk of (more) joint damage. So what DMARDs did for me: they provided very good symptomatic relief but didn't control the disease sufficiently to prevent joint damage.
Inflammation is an extremely complex subject. One of our most knowledgeable members once compared PsA inflammation to a forest fire .... there is nothing wrong with putting out a few flames with NSAIDs such as Naproxen or even perhaps with complementary remedies such as turmeric. And it would seem to be likely, though it does depend on the individual, that DMARDs put out quite a few more. However the research suggests that biologics are the treatment that really does the best fire-fighting job for us. It is extremely frustrating that there isn't some really categorical research, widely accepted by all rheumatologists and disseminated to patients, about the efficacy of DMARDs in controlling the basic disease process. I've been looking at the Gladman & Chandran books again and even they hedge their bets somewhat, though they do indeed cast doubt on how far DMARDs can limit radiographic progression, i.e. discernible joint damage.
I'll 'fess up ... though I think I have done already, if I had the symptoms you have and if, IF, I felt fighting fit overall, I too might hesitate to start DMARDs. I'd take responsibility for that decision, knowing that it did carry risks, not least of which is the delay it would incur in starting biologic therapy (given our stupid system) were my disease to become more severe. I'd watch myself, my health, carefully while getting on with my life and I'd aim to find a rheumatologist who would agree to monitor me, they may exist! Nobody here is trying to threaten or scare you, we're just tying our very hardest to share everything we do know with a fellow patient. I hope you get some good information from your rheumy, let us know what happens.