Works pretty well for me, there's a little profile icon in quick settings to switch
Err... I use a Windows phone, even though I'm normally a Linux user. I kinda like it.
I suspect that it's a feature dropped from many/most customized versions of Android.
And where do you suppose this data will come from? Maintaining something of a plausible and active social media presence is not without it's efforts, nor is creating a profile that would stand up to some scrutiny.
If people aren't really looking it won't matter much, but if they are and getting something that seems fake it might end getting you in much more trouble.
Because they're personal devices. And even if they had, 99% of the population wouldn't even know how to begin using them (like they don't have an extra profile on their laptop).
At most phones could use an easy "don't let the person I gave my phone to check some pic see my dick-picks" mode or similar.
If it is a totalitarian regime, they'll just kill you. If you're ever really in such a situation, a blank phone is probably the worst thing you can give them.
Instead, why not a dummy profile that's complete with user activity, social media presence, and showing active harmless use? Why not multiple profiles?
For the rest of us, those who are not spies traveling in totalitarian regimes, what this means is you can hand someone your phone to let them use it. It means you can let your kid use it and not expect to get it back with problems. You can even make the profiles based on the password, so that it only appears to have a single account.
Realistically, the biggest threat is theft. This doesn't hinder theft protection at all. It can still have the same protections, while just offering additional profiles.