I'm guessing all the people suggesting to ditch WhatsApp have never been to Brazil. Everything there is done with it, you can buy groceries, medicine, do banking, get services, take out, etc... Getting the whole country to change will never happen. So, yes, while some of us do install Signal, none will ever uninstall WhatsApp...
We're seeing the fallout from a commercial service used for public interest communication falling in real time with Twitter, so many public service things that depended or still depend on Twitter have outright broke as it turns into raw sewage and people flee it. That should have NEVER been the main communications medium, and now the price is being paid. I understand as i too am in a place where WhatsApp is near-mandatory, but this is something that WILL have bad consequences sooner or later.
Yup, WhatsApp is basically the Brazilian WeChat. If I uninstall WhatsApp I basically lose contact with my mom and a bunch of other people since I live in Canada.
The UK isn't quite that far, but it's absolutely the dominant text messaging and calling app in the UK. Nobody uses the built in Android or Apple tools anymore, and I'm as likely to receive a WhatsApp voice call as an actual phone call these days.
I have Signal on my phone, but I've literally never had a cause to use it; I've simply got no contacts on there.