I don't believe anyone has denied it happens....the difference is in the Mallon case, it was witnessed. The rule requires virtual certainty that it did happen, not the potential that it could happen. That's my issue... Now precedent has been set that virtual certainty can be attained with logic along the line of "based on what I saw, nothing else is as likely to have happened" and that, to me, isn't virtual certainty...but I am not a roles official. This guy is trained to understand the PGAs norm for this defintion. I'm sure the head of the Rules Officials will defend that decision - and it's good enough for me...it just means I expect to see this rule applied a lot more in the future, in similar cases.
The judgment was never based on "nothing else is as likely to have happened". The judgment was based on a fan seeing the ball come to rest in an open area with no bushes or anything around it and then the ball wasn't there. Assume for a second that the witness did see the ball come to rest in open ground. What other possibility is there?
It is similar to if you hit your ball towards a water hazard, but there's a bank for it to roll down that you can't see to get in the hazard. If when you get there the bank is cut down to fairway height and there is nowhere else for the ball to be, that qualifies as virtual certainty that the ball went in the hazard. If there's long grass on the bank and the ball could be lost in that, then you have to treat it as lost, even if it seems likely that it went in the water (unless you can find the ball in the water).