There seems to be some principle in play where the misuse of a communications channel rises to the point where it's annoying but not quite unusable. If I got 20 junk calls a day, I'd have to turn my phone off. As it is, it's at nuisance level but still usable.
As I recall the service was also extremely inexpensive as part of a DSL bundle. It is true that the landline was a powerful spam magnet, much more so than my cell.
If the power is off for days it means the Apocalypse or WW3 has happened.
Just this last winter thousands in New Brunswick were left with no power in the dead of winter for over a week.
In your case PSTN was the "stable fallback" but there is nothing inherent in the technology that makes this so. Your phone stations still need power, and if they don't have backup power they'll be dead as well.
Cables have a bigger chance of breaking if they're in the air, less so if they're buried. Of course, PSTN, power and fiber can all be both in the air or buried. There's nothing inherent in any of them that make them more "resilient". So if you live in an area where your PSTN is buried and your power lines aren't, it might to lead you to conclude that PSTN is "stable", in fact there's nothing about PSTN in itself that makes it so.
In a lot of places, cell towers will have backup power as well, and so will fiber networks, and your power network might be (should be, probably) buried and better protected than your other cables.
AFAIK, it's not super-cheap with Comcast especially as it uses a different modem than my Internet service.
One of the reasons that landlines are more of a spam magnet is that a lot of call types are exempted from the do not call list on landlines but not cell phones. There may be other reasons as well.
And my parents, who are old enough to be your grandparents? Ditched the landline a couple of years ago. I have no idea what the demographics look like for hardlines anymore.
I despise phone calls. They are blocking, synchronous, distracting, painful (having to hold a phone up in the cases I'm not at a desktop with a softphone and headset), I hate repeating myself whenever I need to read a password or username or email or anything (I have a non-.com email too, so many call centre people have literally zero idea what to make of this). Any time I have to make a call it's a multi-hour ordeal, repeating myself numerous times, on hold for half an hour or more. With phone: I don't know who you are, I don't know your number, I'm not going to verify anything until I can positively identify the caller first.
I've not had a landline before. My first ever phone in primary school was an Android. Where I am, it's not even possible to get an ancient legacy physical landline service - all available providers are transparently be VoIP (like Comcast).
My only experience with phone calls has been automated spammers and PagerDuty during an oncall outage. For personal, if it's important, email me, I reply in under 60 seconds from anywhere. I get push notifications. Not a single one (I cannot even think of _one_) of my friends like phone calls: I don't remember their numbers, they don't remember my numbers, we just message each other on Discord or Messenger or Hipchat or [...]. Most of them get actually quite pissed off if there's a standard voice call that isn't a life threatening emergency. Worst-case is iMessage/SMS.
For work purposes, if something is down, message me on Slack or something. I see your username and team, I can find what's wrong while replying. If you call me, it's a waste of time during a high priority outage if that.
Of the residents I know for sure do or don't have a land line, they are the only ones.
- Until we switched wholesale to a videoconferencing provider, I pretty much needed a landline for work purposes. In addition to just routine conference calls, our webcast provider wanted us on landlines when we gave webinars and I had little desire to go into the office at 11pm at night for the Asia Pacific webcast slot.
- I get poor cellphone reception at my house. Not really an issue now with WiFi assist but I pretty much needed a landline (actually Comcast triple-play) before that.
- I preferred having phones throughout the house and having an emergency backup.
- I like/liked the ability to give out a legitimate phone number that is not my cell.
The ringer on it is turned off though, I've never given out the number to anyone. Nor do I ever use it.
It's nice to know it's there though, I guess as a last resort in emergency situations.