Kidding aside, it does seem like VR probably has value as a kind of exposure therapy..
Likewise, if you have a fear of spiders bad enough that it interferes with your quality of life, you likely want to be desensitized to spiders.
[1] https://money.cnn.com/2016/10/16/technology/fearless-vr-spid...
But a regular and 'by design' aspect of a game, presumably online?
Dunno if I, as an arachnophobe who plays plenty of games online-trust griefers not to ....well grief with that kind of power, heh.
A multi-player spider game sounds potentially terrifying.
I would agree that VR can help with PTSD, but only in the same way as drugs can help with disease. Doesn't mean to say that drugs don't also cause huge problems.
The devil, as always, is in the details and life is not simple.