Rotting, sweaty human hands and fire to name a few.

Nothing, this is why they have both.

It isn't fast enough for mortgage backed securities. Each transfer of ownership of the mortgage requires a separate transfer fee paid to the registry.

Moving from a paper registry at each county clerk (in the US) was a part of the 2008 financial meltdown.

I am pretty sure they have that too.

fires? floods? documents getting lost/misplaced/stolen/destroyed?