Earlier quoted context omitted.
My biggest concern is for the people relying on the big platforms you mentioned but not using them to build their own lists and lines of communication with their clients.
Agree. The big platforms make it all way too comfortable for everybody. And I get it completely. Over the course of years, Google and the likes probably have more phone numbers of my contacts than I have. Only three weeks ago I made a text file with every name and number in it, so I have a safe copy for myself.
You shouldn't have to worry about suddenly losing your list of contacts. Google should be required by law to provide your data to you in cases such as account termination.