Well, I still lock the front door with the deadbolt at night although it won't stop a mob from breaking in, it's good enough to keep me reasonably safe against normal threats.

Also, actively circumvent protection devices is proof of malice and possibly even criminal intent (remember DMCA?) so I don't see your point.

Yes, because awareness does not automatically mean ability to circumvent.

Has there been any one year period in the last twenty years (NeXTSTEP for the first few years for MacOS) where there were not plentiful kernel exploits for Linux, MacOS, and Windows?

I don’t think so.