The reasoning seems to be like this: Native -> user mode -> system calls -> slow WASM -> kernel mode -> no-system calls -> fast I guess, they can check what

The reasoning seems to be like this: Native -> user mode -> system calls -> slow WASM -> kernel mode -> no-system calls -> fast I guess, they can check what a WASM program is doing before they run it, so it doesn't have to be isolated outside of kernel mode.