Comment by sevensor
Getting your program to render the same on different platforms takes a lot of work the user will never see, and that goes double if you actually want it to behave the same. There are some very deep problems you have to work through, like what behaving the same and rendering the same even mean. Same window decorations? Same menu layout? Same dialog boxes? How are you doing font rendering? How much do you embrace platform defaults versus steamrolling over them in the name of uniformity?
You're not wrong, but making these sorts of arguments was the start of me being managed out of that company.