If everything remains perfect on an engine, we wouldn't need mechanics. Analyzers let you know when things are no longer right. Points cams wear, points followers wear, points slip... all of which have an effect on timing. Then there is also the ability to affect the thetaP timing with the blue lever. Any gasoline burning recip engine is just a small margin from detonation when properly tuned and making efficient power. As I said, they aren't about knowing how to lean, analyzers are for knowing when things are starting to go wrong before they get destructive.
I would suggest that you read the regulations that go into aircraft engine certification and see what margins are required by the FAA at a minimum, and the operating conditions under which these things are tested.
Then I would suggest that you actually go out and do some experimentation to see just how much of an impact factors such as CHT, IAT, Oil Temp, mixture, and RPM have on detonation when lower powered engines are run on 100LL. Judging from what you say now, I believe you would be surprised at the end result. There are many factors that influence knock, which is one of the reasons why it is so misunderstood, especially from a practical application sense.
We have one fuel to work with here. That means that the high stress engines (with a high octane requirement) and the low stress engines (with a low octane requirement) are getting the same anti-knock characteristics of the fuel. The reality is that some of them need it and some of them don't.
My Ford does just fine knock wise on 87. I don't know how much it knocks, but I'm going to guess pretty close to not at all. If I put 91 in it, it will do even better. Yet if I put 87 in my twin-turbo Mitsubishi, I'll melt a piston...
All that has nothing to do with getting any engine to detonate by changing mixture.
You can do a great deal of damage by running too hot, but you can't harm your engine from detonation by reducing or adding fuel.
While I understand that you're speaking to the ultimate change that causes the damage (the high temperatures and pressures), those events are frequently precipitated by a change in fuel flow. The red knob is the #1 tool that the pilot has to induce or get out of detonation on the engines we fly. I realize that the big old radials that you flew back in the day may have been different (I have no experience with them), but an R-2800 is not a 520/540/etc.