AFAIK it's a more native focus on 64bit rather than slapped together support from previous OS's. 32bit mode is emulated via WOW64 and the processes are isolated from the 64bit environment. 16bit would be an emulation on top of an emulation.I have a collection of old games from the early 90s id like to run whenever I so desire without having to use any other program like dosbox.
Not sure why 16 bit subsystem is not in 64 bit versions of windows 10 except the normal obsolescence Microsoft is known for.
In fact the subsystem could be added but only used when a game requiring it is started and terminated when the game is terminated.
geez...makes me wonder where I put that leisure suit Larry game now.....eh... it was on a floppy and my pc's mobo does not have a floppy port