The Ilford 72 exposure rolls were a thin base -- but there was still the major problem of finding a developing reel (or even a dip-and-dunk system) that could handle film that long (in a leader card or roller process C-41 system, it's not a big deal, of course). Also, some modern cameras may have problems if they don't sense end of film before about frame 40, but it doesn't matter much -- AFAIK, no one now makes a 35 mm film thin enough to put 72 exposures in a standard cassette.