Still, it illustrates that 2/3 of developing country households don't have PCs. If you look at the stats for developed countries it's closer to 80%, but combined it's less than half worldwide, and even in developed countries I'll bet that skews very heavily away from the poor and lower middle classes. So there are a heck of a lot of people without PCs, even if you allow that some of them may have a PC at work.
This is true.
That's a LOT of people who might benefit from using something like Dex.
But I don't think this conclusion follows.
If someone doesn't have a PC, they probably don't have a monitor, keyboard and mouse/trackpad at all. They're also less likely to choose Samsung in particular as their phone vendor. But even if they do have a Samsung phone, odds are they won't have anything to do connect it to.