You don't necessarily "need" it but what feature of Win11 or OSX is worth the making all existing software inoperable? Can't say I have seen one outside of gets security updates.
I don't know, you could do something totally wild like re-imagining the filesystem... I, for one, would love a flat blob store organized in some other way than folders or filenames. I think there's tons of interesting things that could and would be explored without backwards compatibility holding us back. That's how the original OS X came to be.
But what I really don't get, is why we need backwards compat when computers can run computers, and old operating systems hardly demand resources on a modern computer.
