Phrasal verb: call off (call vs. call off)

Hi, could you please shed some light on how to the verb call is used in the following sentence:

Such arrogance! A conclave is not some American baseball game you call on account of rain.”

I mean, why does it not read “… you call off on account of rain.”

Thanks in advance,

TOEIC short conversations: A visitors asks for directions to an office[YSaerTTEW443543]

Because when we’re talking about baseball games and some other events, we shorten call off to call. Of course, you can do this only with things that can be called off, and for which “call” does not mean to announce. You must call off a meeting that you cancel, because to call a meeting means to announce and organize one. You have to call off a strike, because to call a strike means to tell the workers to start a strike. Since we never use “call” in the sense of organizing sports matches or trips, you can say that you call (or call off) a baseball game, or call (or call off) a trip.