IBM was ridiculously huge, both by actual IBM hardware, but also by clones, and manufacture of S/360-compatible systems. Even many wildly different computers often had third party interfaces to hook up S/360 channel devices, or controllers for the actual devices (it was common for channel devices to be linked like this: S/360 -> channel processor -> controller -> device-specific connections -> actual device).

Even the fact that we format code usually to 72 characters is related to 80-character standard S/360 punched card, where the remaining 8 characters were used for sorting/comment code, and why professional terminals (as opposed to things like 40 column mode on home computers) had 80 column displays.

Also, had ASCII been ready earlier, S/360 would have used ASCII as default encoding - IIRC S/360 team decided they can't wait for ASCII to be finalized and they needed to start design and making of various devices that would have to be encoding-aware, thus EBCDIC was born.