@jon_alper It was reverse-Sherlocking. Sherlock took over the functionality of things that weren’t already in the OS.
Virtual Memory was in System 7.0 but was broken in many ways, and there was really nobody maintaining it. Connectix took the gamble of replacing an OS component that wasn’t working very well and it paid off for them for several years.
Speed Doubler was another Connectix product that took advantage of Apple’s inattention to a few other OS components. I fixed the File Manager’s disk cache performance in System 7.6 and reverse-Sherlocked part of that product, too.