It depends on what you consider a serious work machine. Half the time, I couldn't do my job on it because I need Xcode and Android Studio, neither of which run

It depends on what you consider a serious work machine. Half the time, I couldn't do my job on it because I need Xcode and Android Studio, neither of which run on it (yet?). But days where I'm in meetings or just writing docs, I could (and have) gotten by on just my iPad. My barber runs their business on an iPad, using a native app to handle scheduling and payment combined with a Square reader. Musicians can carry their entire musical portfolio on one, and get paid for their work after. Realtors can do nearly all of their daily work on one since it's largely web-based these days. Our use cases aren't the only ones.