Seems to me one of the main things that got people to move away from Whatsapp en masse a few years ago was a rumour that they’d added a backdoor to it similar to the one Sweden is thinking of demanding. If an unfounded rumour did that much, the real thing might do substantial damage to Whatsapp as well if they were to go along with it. It probably wouldn’t completely demolish it, as it would for Signal — or at least its demise might take longer.