See, now I'm fine with that. I pay for Netflix and I want what I pay for to stay ad-free. Having an ad-supported tier with no fee in addition to that means that there are options for other people without enshittifying my experience.
That's a world of difference to what Amazon have done where they've shoved ads into the service that I thought I was paying for, and then offered to charge me even more to get my original ad-free service back.
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.