AMPS was designed prior to divestiture being a thing, but even with that in mind, no one really knew how fast cellular usage would take off, and so the carriers

AMPS was designed prior to divestiture being a thing, but even with that in mind, no one really knew how fast cellular usage would take off, and so the carriers were caught somewhat flatfooted. Consider that most cellular networks were originally built with omni antennas, not panel antennas, so the ability to reuse channels and channel-per-site density was noticeably lower.