The old call signs, like WBZ, WTIC, WEAF, WJZ, WCAU, KDKA, WGY, WGN, WOO,
KYW, KOA, KFI didn't mean anything.

Wrong, on at least two counts:

WGN: World's Greatest Newspaper (referring to the owner, The Chicago
Tribune)
WTIC: referred to owner Traveler's Insurance Company