Comes down to risk management. What are the chances of the land titles office and every "offsite backup site" being destroyed pretty much simultaneously?
If that happens, then there will be a percentage of people who do not have their Certificate of Title.
Even then, if that was to happen, how many people would not have other substantive proof of ownership (eg. Council Rate records, bank mortgages etc). All of which offer prima-facie recognition of ownership.
(Whether that would be accepted, of course, is another matter).
Problem is, even if you did have the Certificate of Title (Copy), and the titles office burns down, it places real suspicion on all the copies since they are therefore much more open to forgery and fraud.