Games

The flute doesn't make for a good example, as the end user can take it and modify it as they wish, including third party parts.

If we force it: It would be if the manufacturer made it such that all (even third party) parts for These flutes can only be distributed through their store, and they use this restriction to force any third party to comply with additional requirements.

The key problem is isn't including third party parts, it is actively blocking the usage of third party parts, forcing additional rules (which affect existing markets, like payment processors) upon them, making use of control and market dominance to accomplish this.

The Microsoft case was, in my view, weaker than this case against Apple, but their significant market dominance in the desktop OS market made it such that it was deemed anti-competitive anyways. It probably did not help that web standards suffered greatly when MS was at the helm, and making a competitive compatible browser was nigh impossible: most websites were designed for IE, using IE specific tech, effectively locking users into using IE. Because all users were using IE, developing a website using different tech was effectively useless, as users would, for other websites, end up using IE anyways. As IE was effectively the Windows browser (ignoring the brief period for IE for Mac...), this effectively ensured the Windows dominance too. Note that, without market dominance, websites would not pander specifically to IE, and this specific tie-in would be much less problematic.

In the end, Google ended IE's reign by using Google Chrome, advertising it using the Google search engine's reach. But if Microsoft had locked down the OS, like Apple does, and required everything to go through their 'app store'. I don't doubt we would have ended up with a similar browser engine restriction that Apple has, with all browsers being effectively a wrapper around the exact same underlying browser.