Your statement is correct, but doesn't tell the rest of the story.
The disk has an onboard data buffer, usually implemented in DRAM. That DRAM chip is likely sourced by the lowest bidder, and it is likely not to have either parity or ECC. Also the CPU used in the drive can introduce its own data errors and corruption. It doesn't even have to be hardware. A firmware bug can also corrupt data.
There are numerous buffers and storage elements involved in transferring the data to/from the disk's onboard memory to/from the computer's RAM. Many/most of those elements are not checked for parity. Data is subject to corruption in transit.
That's what makes a filesystem like ZFS so interesting. It checks the entire data path. It doesn't care where the corruption occurs.
The disk has an onboard data buffer, usually implemented in DRAM. That DRAM chip is likely sourced by the lowest bidder, and it is likely not to have either parity or ECC. Also the CPU used in the drive can introduce its own data errors and corruption. It doesn't even have to be hardware. A firmware bug can also corrupt data.
There are numerous buffers and storage elements involved in transferring the data to/from the disk's onboard memory to/from the computer's RAM. Many/most of those elements are not checked for parity. Data is subject to corruption in transit.
That's what makes a filesystem like ZFS so interesting. It checks the entire data path. It doesn't care where the corruption occurs.