Once Signal is backdoored successfully (in this alternate timeline) you go after WhatsApp, RCS, whatever other encryption you can't bypass. Other countries follow suit because Sweden did it (like an infamous single study out of the Netherlands that affected global health policy.)

The goal is no privacy. Because terrorism. Or the children. Or espionage. Just pick one and speak against them directly and you'll find many arguments why the government needs access for any of those reasons. People love going to bat for giving up rights.

I forget who said it but you cannot have a civilization without secrets.