I was looking through my traffic this evening and noticed over the last seven days nearly half of my traffic has been from the “unknown mobile” browser. Now, I can only guess, but seeing that most of my visitors are on an iPhone and most are coming from Facebook, it’s likely the in-app browser.
But I don’t know.
And that’s why your content should be available to any browser. Developers like to be fancy and get in the way of allowing visitors to accomplish the core task—usually reading some text or submitting a form—regardless of browser choice.