We are both responding to: "I love my iPhone but I really don't get this. Apple only has 31% of the smartphone market and Android has 59%, for example." and in turn the original article

In this context the interesting definition of 'market share' is the one that focuses on platforms. There isn't very much interesting to be gleaned by making the distinction that Apple has a bigger market share than Samsung as Samsung and other Android OEMs collectively benefit from Android's market share.