Jethro wrote:

....
I just went thru the exercise of throwing my main power breaker to see
if I lose all dial tones that way. And I do not. Unlike with a true
power outage during which I lose all dial tones, whether the phone is
cordless (portable with a base) or corded (connected to the wall),
with the main breaker thrown I only lose dial tones for the cordless
phones. That is as it should be.

So I still do not know why I and some of my neighbors (but not all)
lose all dial tones during a true power outage.

You don't need to know. It is now clearly the telco's problem.
If they are unwilling to deal with it, you can complain to whatever
regulatory agency that oversees telephone companies in your state.
You could even tell them that you couldn't dial 911 during the last
outage (of course you didn't try, but don't mention that).