That's not what they were doing though. Apple is the prime example here. To license a cellular modem from Qualcomm, they'd need to license everything the SOC covers, because it isn't ONLY a modem - as a percentage of the MSRP of the device itself and not the components. They don't need the CPU, their A series chips are better. They don't need the GPU, theirs are better. It includes image processing, they have their own. It includes GPS, they have their own. This also includes software licenses that they don't need, such as the fingerprint scanner software Android uses. There's many other patents they've put into their SOC, but Apple only needs the modem, but Apple would have had to pay for everything else that goes unused.
Apple charges royalties for the lightning connector... not some random and fictitious Apple Serial Bus that nobody needs to use because of USB. Just the connector.