Notably the PC standard meant things were interchangeable, not "interlayerable". You picked a CPU, you picked an OS, you did not have to emulate or virtualize whatever you wanted on top of what was imposed on you. Imagine that 30 years ago someone pitched a PC that only runs a specific OS and the only way to run anything else is on top of that like an app. You'd think "ridiculous".
Today having a device that runs as sealed monolith both HW and SW wise, and all you can do is run stuff on top of that without the ability to replace anything is considered a good sign. Tells you where we're going.