为什么在ruby，php，asp.net mvc等语言中使用HTML标记代替XLST将XML转换为HTML？

I just learned about XLST on stackoverflow today (I love how in computers you can program for years and constantly have 'darn, how did I not know about that technology' moments). I'm wondering how popular XLST it is for web development? I've worked on a few websites (using php, ruby, and asp.net mvc) but I'm not a web developer by any means.I just learned about XLST on stackoverflow toda