I don't doubt that PFOs are responsible for a significant number of bends. However I don't know how large this number is. I remember a talk a couple of years ago where the 1 in 4 (close enough to 30%) stat. was mentioned. However most of those PFOs are very small, and the percentage of people with large PFOs is much smaller.
Something my chamber operator said to me when I was in the chamber a couple of years back is that PFOs are "Sexy". People in general like to have a
reason for things, and so much the better if the reason is not down to them.
The guy said he'd seen quite a few people who had been bent and recompressed and when diagnosed the first thing they asked was whether it was a PFO, despite short surface intervals, sawtooth profiles, and probably dehydration from being out on the pop the previous night.
That's not to say that PFOs don't cause bends. But I think people's perception of PFOs is somewhat warped, but then that's human nature.
Janos
PS - Digressing slightly but there's an interesting paper on people's perception of risk here:
<Click me>. It starts off slowly, but there's a few interesting bits about risk there. For example, people are more likely to accept a risk if they perceive themselves to be in control of the situation. Eg you feel safer in a speeding car if you are driving, compared to when you are the passenger.