The FCC delayed cell phone technology by at least 2 decades. AT&T delayed computer networks (pre-internet) by insisting on owning every device that connects to it, so modems had to use slow acoustic couplers.
True, it didn't fit the rest of the list. They did do a heckuva lot to keep people from competing with them - and to prevent better technologies from coming along (as otherwise mentioned, acoustic couplers. fax machines also fit in there).
Bell also had a nasty habit of - when forced to compete by the government - physically sabotaging interconnect points.
