It's a silly flag to use as it only works when running 32-bit Windows applications on 64-bit Windows, and if you're compiling from source, you should also have the option to just build a 64-bit binary in the first place. It made a degree of sense years ago when people actually used 32-bit Windows sometimes (which was usually just down to OEMs installing the wrong version on prebuilt PCs could have supported 64-bit) if you really wanted to only have one binary or you consumed a precompiled third party library and had to match its architecture.