Please show me those chipsets, current or old, that do data checksumming from memory to the storage controller, and I will admit that part to be safe.
I know the data is checksummed on the drive. You dont need to repeat yourself.
People touch their internal computer components all the time, potentially inducing electrostatic hidden malfunctions. Memory corruption happened to me also, although I don't know if it caused data corruption in storage (I happened not to have checksums of all the files on my drive then), but it would be trivial for this to happen.
I would expect ZFS and data checksumming being actually of more use for home users, who run on cheap commodity hardware (often self-assembled) with little error correction & detection (yes, the disk drives do do error correction, even the cheap ones, but none of the other components do) and with buggy firmware.