I'm not convinced by this post really, I'm sure pointing your camera at the sun with it on will cause damage. But I don't believe that smartphone cameras are as susceptible as photography cameras. If they were they'd have a physical shutter.
But they don't so either the sensor is harder to damage while it's off, or the smartphone lens just isn't big enough (or focused enough) to be an issue. Not to mention they have uv and infraded filters too.
Another other explanation I can think of is that sun isn't likely to be barreling down a smartphone lens often enough to be a problem.
Where I live in north america, the sun never resides directly overhead, so maybe that minimizes damge.
Or maybe it just requires a lot more exposure that its not likely to be a problem for the life of the device.
Either way, unless you are an optical engineer for a smartphone company, I remain unconvinced. It seems to be a rather rare problem that most users shouldn't worry about.