With the events of ghostbusters 2 the more interesting idea is that somehow someone created an artificial ley line nexus on manhattan so powerful that it nearly created a god and it was put down by muggles.

I do agree that the GBII events would mesh very well with the Wizarding World as we know it. The painting of Vigo the Carpathian could easily be viewed as a Horcrux, indeed his plan to transfer his essence into a human body would align extremely well with that premise.

So in this crossover scenario I would posit that baby Oscar was specifically chosen due to his being a Wizard by birth, perhaps a distant descendant of Vigo himself so that his new body would have the capacity to perform magic. When that opportunity is snatched away, Vigo senses that Ray Stantz is actually a latent Wizard himself that has flown under the radar his entire life but his obsession with the supernatural provided him with a subconcious outlet for his magic.

Which is why the Ghostbusters gear even works in the first place - Ray is a bona-fide scientific genius in the Muggle world he grew up in but in the end he was augmenting his (and Egon's by association) inventions subconsciously using magic. Which to me makes sense as to why nobody else would have been able to reverse engineer their tech and copy what they were doing.