I'll use my Father as an example. He works for Autodesk, before that he worked for Revit (when they were a tiny startup before Autodesk bought them out). He writes code in C++ mostly (I think some C# these days). He doesn't use HTML or CSS, and has never learned either. Not because he can't, just because there's not been any point and because the amount of effort that would take is large enough to not be worth it. Why spend several hours or days of extra effort just for a blog post? Not to mention the extra money needed to buy a domain and hosting.