microHDMI-HDMI is passive, as mentioned by another poster. The issue here is the software - two standard HDMI (electrically) ports can be really well supported

microHDMI-HDMI is passive, as mentioned by another poster. The issue here is the software - two standard HDMI (electrically) ports can be really well supported by all the software, meaning that it can all be multi-monitor friendly. USB-C uses hardware so wouldn't have the support, see the issues with HDMI-VGA when the first pie came out. As an aside, they probably went with microHDMI as they're smaller (and hence cheaper in cost and area) on the board, and put less force with heavy connectors. Lastly, many android tablets have the microHDMI connector so they're easy to get hold of (first world anyway).