Sorry Frank, Well-T -- it's just not the case. In situations where VRBO advertisers are hacked it's similar to the spoof email you might receive from someone posing as your bank. The homeowner gets sucked in entirely off line from the advertising site. The criminal initiates a false inquiry with the owner in order to learn the email account, then they know who to attack. Please keep in mind that VRBO and similar site are simply advertising vehicles. I doubt you would be saying the same of the New York Times if a scam artist happened to place an ad in that newspaper as their first step toward duping people with more money than sense.
Seriously, there HAS to be some level of consumer awareness and responsibility. The person in question wired money to a total stranger. Sorry, but no company can prevent that kind of ignorance.
Consider too that these are the rare exceptions. You have not stopped driving your car when someone crashes and dies. You acknowledge the danger, and if you are smart, you keep driving, and exercise caution.
I am an owner who advertises on HomeAway, parent company of VRBO, and have a very good understanding of the challenges of thwarting con artists and the exceptional measures HomeAway and VRBO take to protect customers.