Tencent's super-app WeChat has become ubiquitous in China, prompting Elon Musk to muse about the absence of an equivalent outside China. It is with regret that I must confirm that 2009 already counts as the olden days. This was the year in which Apple started saying “there’s an app for that” in its advertisements. The phrase was much repeated, much parodied and super-effective. The following year the iPhone maker registered it as a trademark. Looking back on those original ads, Apple’s need to explain concepts we now readily understand can’t help but bemuse. “What’s great about the iPhone is that…