I have a friend whose mobile phone died over the weekend. Another close friend had their phone drop into water. In both cases their mobile number was the way people stayed in touch with both, either by phoning them up or by text. And, since in both situations, their phones were dead, they were out of luck from the moment their phones stopped working,
In the later case I received a Skype message telling me what happened followed by her asking what to do. Unfortunately going into the AT&T store to get a temporary replacement phone (i.e. a burner) led to her being "sold" a new phone with a pre-paid plan. All she needed was a phone as the SIM card was still perfectly able to function. Net result was a waste of $65 for the unlimited whatever, as her existing plan and number were still usable.
The second person had their phone die also. She sent me a message via Facebook Messenger. In this situation, she did that from her home computer and now will be out of touch. With all of these modes you can still stay in touch, but the beauty of a Google Voice number is it would move from device to device and still function as the mode of staying in touch with a breaking of habit.
Basically, the last two places I expected to hear from either of my friends was via Skype or Facebook Messenger, and in the case of the Messenger person, I was actually concerned about her when I hadn't heard back from a text sent earlier in the day.
Now, had I had Skype running on all my devices as I used to but have abandoned sometime back, I would have seen the first message and call. In the second case if I was living inside Messenger 24/7 I would have seen that instantly to. But I'm not.
With GoogleVoice the messages come into their app and to my email so nothing is missed. I get desktop notifications inside the Chrome browser, so it's almost impossible, except when I'm sleeping, to miss a GV call or message, so in both cases, if the phone losers had GV they would still be connected to everyone, not miss messages or calls.
When Craig Walker and Vincent Paquet launched GoogleVoice as GrandCentral in 2006, the idea was "one number for life" and in more ways than just words it still is.