I use it all the time. For example, some parent from school sends me a message if their kid can play with my son tomorrow. I forward it to my wife so that she's in the loop. Super handy.
My sister sends me a nice photo of my kids. I forward it to the in-laws' family group (who live far away). They love getting pictures of their grandchildren. Super handy.
I suspect that it's stuff like this that the feature was designed for. I think it's hard for UX designers to imagine that there are millions of people who will believe anything they're sent and who will forward it to everybody. And that it's somehow the app's fault if people do it.
I mean, I'm no big fan of Facebook Inc, but where were the outraged news paper articles when people forwarded extremist nonsense, scams and viruses to their entire email contact list? Why didn't they demand action from, eh, whoever designed SMTP, immediately?
WhatsApp has no fancy engagement-maximizing algorithms that we can get angry at. It's really just texting with groups and mixed media. Forward something to 100 people, 100 phones are going to buzz.
Correct me if I'm wrong, but I understand that people in the US don't use WhatsApp because texting is free. Do people in America get angry at telcos when people send violence inducing bullshit text messages to each other?