It's a little related. The languages typically used for iOS programming encourage the use of data types whose size matches the CPU architecture's bitness. Thus, careless programmers will end up using 32-bit integer types on 32-bit devices, and 64-bit types on 64-bit devices.

I really doubt this is in any way linked to Apple's reasons for dropping 32-bit, though.

"The reason that some iOS devices are unable to connect to live chess games is because of a limit in 32bit devices which cannot handle gameIDs above 2,147,483,647."