NAS (probably SAN in this case) systems are perfect for redundancy,
Nope. NAS is intended to provide a single logical drive as the storage for multiple hosts. If redundancy is a requirement, what you need is each host with their own storage separate from the others, in its own cabinet, with its own power supply. Think of air data computers. Having multiple ADCs all fed from a single static/pitot system is the logical equivalent of using NAS (one logical disk drive) to feed multiple servers.
the fact people (read ADMINS) keep confusing redundancy,
They don't confuse it. Its just laziness. One physical copy of data is easier to maintain than having to update multiple systems. Or update one master and push copies to the slaves.