“Depending on your settings, you can also periodically back up your WhatsApp chats to Google Drive”
“You can use the export chat feature to export a copy of the chat history from an individual or group chat.”
I haven’t checked the full backup, but exports of individual chats are easily readable (zip with a .txt of all texts in the chat and individual images, IIRC)
The individual exports work fine, but it’s very tedious to go through every conversation individually.
So no, at least SMS is not a social network.
I don't like WhatsApp anymore but it was in its time my favourite social network. I had all my important groups there, used it exclusively to communicate with close friends and family.
It was the place were most images were shared and discussions were held and so on.
Even iMessage seems very much like a 1-1 messaging system.