Omnipresent in the ocean, yes. Likely in captivity, yes. Inevitable, no.
It is essentially impossible to establish that ick is NOT at all present in a system, but my experience has been that after doing a proper and reccomended treatment, and then preventively treating any new additions - I haven't seen the slightest hint of a symptom of ick in my system for about 8 years now. I only have a few fish, I almost never feed (anything other than what is self sustaining in the tank), when I do feed it's usually just a pinch of flake or pellets (maybe once a week at best). I have had multi day power outages, temp spikes, low temps, and various other stressors. I can't prove my tank is truely clean of ick, but having done a reccomended treatment based on well known science and having no re-occurance on all these years, I'm fairly confident that no stressor is going to cause ick to pop up other than actually introducing it.....
Is treatment for everyone? No, not at all. Is it possible? everything science has learned about the parisite indicates that it is possible.
I'm not attacking anyone's opinion or experiences, but eradication is possible even of the vast majority of anecdotal experiences run counter to that fact.
Edit, also please note that the linked article above talks about "hyposalinity" as keeping the SG at 1.010-1.013. (Effective hypo treatment requires 1.008-1.009) It's easy to disregard a treatment when you don't do it right
