The main gigantic upside of a 64-bit process is the ability to support more than 2 GBytes of RAM (pedantic people will say “4 GBytes”… but there are technicalities I don’t want to get into here). And remember, there is no downside.
Because there is zero downside, the first time it could, Apple shipped with 64-bit OS support. Apple did not give customers the option of “turning off all 64-bit programs.” Apple first shipped 64-bit support in OS X 10.6 Snow Leopard in 2009 (which also had 32-bit support, so there was zero downside to the decision).
This was so successful that Apple shipped all future Operating Systems configured to support both 64-bit and 32-bit processes. All of them. Customers no longer had an option to turn off 64-bit support.
Apple approach with that of Microsoft. Microsoft offers a 64-bit OS in Windows 10 that runs all 64-bit and all 32-bit programs. This is a valid choice of an Operating System. The problem is Microsoft ALSO gives customers the option to install 32-bit Windows 10 which will not run 64-bit programs.
