> They aren’t sticky enough on their own to avoid people just installing the next one. I think I have used 10 of the things at various points but SMS and email are still massively more popular.
That works in a different way. Today you have WhatsApp and Signal. 95% of your friends are on WhatsApp and 5% are on Signal. Now let's say Signal starts taking over. In five years it's the other way around. This is possible because you can install them both on the same device during the transition.
If you buy a kind of phone that can run Signal but not WhatsApp at the time when 95% of your friends are still on WhatsApp, that doesn't work. You're not going to buy that phone right now because your friends haven't moved yet and won't for another five years.
First you have to spend five years getting everyone to switch messaging apps, and even then you can only switch platforms if the next messaging app to become popular runs on the new platform, which it generally doesn't, because nobody writes apps for platforms nobody uses and nobody uses platforms with no apps.
The usual solution to this is something like wine that allows you to run the old platform's apps on the new platform. But Google prevents that by encouraging third party apps to have dependencies on SafetyNet or some other Google services or code that the new platform can't easily implement as a result of excessive complexity or legal restrictions.