a system that can be scaled 333x or pushed into radically different allocation patterns by changing one or two constants seems like an odd choice for arguing that YAGNI and you shouldn't plan for anything beyond 10x/should plan for a system rearchitecture at that scale. That seems very much like a system that thought ahead and picked meaningful knobs to allow drastic changes in use-case to suit the situation.
Windows NT 4 already contained the code necessary to allow for up to 16 exabyte partitions (https://web.archive.org/web/20010208131204/http://support.mi...), but the hardware it was running on probably didn't support anything bigger than a few terabytes. Sure, every text file takes up at least 2MB, but with an exabyte disk, you probably don't care about wasting sectors like that.