The only thing that precludes Web.config from working cross-platform is the absence of reliable implementation of a cross-platform web server. For example, I do

The only thing that precludes Web.config from working cross-platform is the absence of reliable implementation of a cross-platform web server. For example, I don't even consider Nginx reliable on Windows; some nasty effects are in place. The best home for Nginx is Linux. The best home for IIS is Windows. Cross-platform sounds sweet in theory but in reality it goes down hill pretty fast with subtle defects.