Originally posted as an answer to Why XSLT is not popular for developing web applications?

The first problem with XSLT is that it is a programming language that where you have to write using XML rather than traditional programming paradigms. Most programmers are familiar with C-like languages (Java, C#, C). XML is horrible to write. I don’t know many programmers who want to write code using XML.

The second problem is that XSLT only applies to a very narrow set of problems. XSLT can transform XML documents into HTML, XML, or text. But you can do the same thing in Java, C, JavaScript, Python, C# or any other major programming language. What does XSLT give me that I can’t do in any other major language? If I really like the functional features of XSLT, why not use a fully developed functional programming language?

Lastly, XSLT is a relatively new language. XSLT came out as a W3C recommendation in 1999. By comparison, Java and JavaScript came out in 1995, C in 1972, C++ in 1983, and Python in 1994. It takes a long time for languages to reach widespread adoption.