They need to. Honestly we need a way to completely segregate Chinese and Russian networks off, as well as anyone who peers with them. They are using our open networks to brazenly attack us in broad daylight… it’s time to fight back.
How many ways do they have to transmit to Western networks? Proxies, tunnels, rooted machines, sending balloons with 5G modems that dwell in our airspace for days? I would much rather see a 100:1 defensive effort in operating system security. Lockdown mode in macOS is like Spinal Tap's amplifier that goes to 11. Why not just have 10 be the most secure, and make it go up to 10?
You only need one weak link in the chain. Computer security is effectively an oxymoron.
Because lockdown mode makes a lot of compromises for user experience that most people don’t need to worry about — disabling JIT, for example.