Direct3D isn't the reason why OSX and Linux are second class citizens for AAA publishers. If those platforms had higher gaming market share publishers would do

Direct3D isn't the reason why OSX and Linux are second class citizens for AAA publishers. If those platforms had higher gaming market share publishers would do the work, but as it stands Steam is at 98.3% Windows users, 1.31% Mac users and 0.25% Linux users (http://store.steampowered.com/hwsurvey/ http://store.steampowered.com/hwsurvey/). Linux has an extremely disproportionate amount of work involved for the user base, and Mac OS X is questionable for most titles. The Linux gaming audience is largely consists of tech people that aren't really gamers, but buy games to support Linux gaming, effectively for political reasons, this isn't a sustainable market (Humble Bundle helped indies briefly but the support has faded). Mac OS gaming is largely casual users that once again, aren't really gamers, and it has less to do with Mac's software stack (vulkan vs. metal vs. dx is irrelevant) and more with Mac hardware having underpowered GPUs for AAA games. PS4 and Switch don't support Direct3D, and plenty of big publishers port titles that make sense to mobile as well (neither major mobile platform supports Direct3D).