Sure, but we're not speaking about overall system reliability. We're speaking about hardware dying. RAID will prevent data loss, but your actual disks might fail as often as something from vanilla PC.
ECC RAM will both work-around and warn you about the start of RAM failures before complete DIMM failure.
And sure, consumer drives have the same MTBF as enterprise drives in practice[1], but: when RAIDing consumer disks, make sure that you get models that immediately report read/write errors, instead of retrying, which is the main (or only, if SATA) difference between enterprise and consumer drives.
If you have a nice RAID setup, you DO NOT want a drive to retry a failed block read 15 times before reporting a problem, and causing latency: you want the failed read to be reported immediately, so your controller can pull the same block from a different disk, and start diagnosing possible faults.
