BTW Multics didn't have the first filesystem; its design was influenced by experience with earlier systems like CTSS also developed at MIT. The AI lab's ITS OS also had a filesystem, though inferior in many regards to Multics's design.
An interesting side point relevant to the article: the original intent of Multics was that pages would be the basic data structure, with the filesystem essentially merely a way to keep track of groups of pages when they were not otherwise in use or when a way was needed to refer to them. (The actual initial implementation fell short of this ideal.)
Even if it is, it may not be widespread knowledge. E.g. WoFS, the first embodiement of many ideas found in ZFS and friends, is virtually unknown, despite being developed in the late 80s, and with documents available online.
An interesting side point relevant to the article: the original intent of Multics was that pages would be the basic data structure, with the filesystem essentially merely a way to keep track of groups of pages when they were not otherwise in use or when a way was needed to refer to them. (The actual initial implementation fell short of this ideal.)