Yes - If Best Buy did control the market (i.e. was a monopoly) and then abused it's market position to price-up Dell and force adoption of their own brand, then

Yes - If Best Buy did control the market (i.e. was a monopoly) and then abused it's market position to price-up Dell and force adoption of their own brand, then it would be the same. The difference here of course, is that Best Buy can't control the market in this way because there are other options and customers will go elsewhere, and Dell can sell direct to consumer and through other channels. Apple can control the market in this way, and Spotify can't sell direct to consumer without Apple taking a cut (unless they build a web-only version, which would not be competitive with Apple's own offering). Spotify could go android-only, but then the same issue exists with Google and Google Play Music. Why do you think Apple is in this market? They realized that market control in one industry (the mp3 player / smartphone) could be exploited to get market control of other industries (e.g. music distribution).