Maybe for the real-time cache usage display ? Or performance (in the sense of less noise while measuring) ?
I'm tempted to try it out and see for myself, though.
For posterity; Cpu counters for a lot of things can be gotten from userspace. The linux kernel exposes a lot of things in /proc (procfs) and /sys (sysfs). Programs like perf, slabtop (and probably others, that i can't remember now), use these informations to display more-or-less the same data as this program.