The reliability of the grid is a combination of the technical reliability of the grid and the social ability to reliably coordinate the resources needed to operate the grid. You need both systems to work in order for electricity to flow. As you point out, there's nothing wrong with the grid on a technical level. But the social element failed, so electricity stopped flowing. When the electricity stops, it doesn't really matter whether the power is off because of a technical or a human problem. The lights go off either way.

The wind that shut grid blew at 10MPH. (Granted, it was forecast at up to 45MPH.) Did we not see winds of this strength during the 120 years* that we didn't shut down the grid over human coordination failures? If PG&E had to shut down the grid to avoid fire in light to moderate winds, it was because the people operating the grid were unable to coordinate the resources needed to operate safely under these conditions. What we've seen here is a breakdown of human systems that used to work reliably. We used to be able to operate an electricity grid reliably in moderately windy conditions. Now we can't. That should worry everyone.

* Yes, I know about Enron. That we've had two grid failures in 20 years due to human-coordination breakdown is a huge red flag.

Edit: phrasing, note that the winds were forecast to be stronger than what we ended up seeing