[skunkpocalypse]

> Why don't all silicon chips have glitch and overvoltage detection?

Reliability. This is basically the microchip version of Boeing's MCAS.

The circuit you describe is not only an analog circuit, but is in fact a noise amplifier. You're now shipping a chip containing a noise amplifier that drives the device-wide reset line.

What could go wrong?

The stuff you describe is very, very difficult to get right, and beast-mode insanely difficult to troubleshoot or even diagnose when it goes wrong.

It's also very sensitive to manufacturing variations. So if there is a problem with the circuit, it'll probably only affect a few batches. Which, Murphy's Law and all, will be the batches that wind up in the hands of your most important customers.

Stuff like this can bankrupt a chip company if you get it wrong, and there's no way to be sure you got it right. At most you put it in your super-high-end ultra-secure product line, so long as that line's sales are small enough that you can afford a recall.