There's no transparent support for anything GUI or GPU related. There's no ability to use another hypervisor without rebooting the machine and changing a flag and then changing it back. There's no seamless access to the same filesystem. There's no seamless networking. There's no interprogram communication across the OSes without the (kinda broken) network.

Only the first one is something you get running Linux on bare hardware. The rest are goalpost-moving (and I don't even know what we'd be discussing to make those valid points honestly). And about GUI/GPU, that's actually not a valid point either, as WSL2 has OpenGL support now.