spoken like a lazy storage admin
This article safely reinforces the worst prejudice of storage admins, which is the belief they can do their job and remain ignorant of the applications that run on their systems.
I'm a DBA (Sybase, Intersystems Cache) and a storage admin (ZFS, NetApp) for a cloud company. As a vertical market software vendor, I also deal with our premises customers' myriad other storage systems (EMC, Compellent, Hitachi, etc.). I've seen a lot of good and a lot of bad. The storage system, more than any other component, determines application performance.
There can be a real need for multiple LUNs in a database, even though they ultimately sit astride the same physical disks. Separating data from log I/O in RDBMs is axiomatic. The OS kernel may effectively serialize I/O to a single LUN whereas multiple LUNs have multiple software channels. In other words, you are clearing a software not hardware bottleneck. There could be other considerations in regards cache policies, tiering, etc. that justify multiple LUNs.