Feasibility of "do all application coding in the XML languages"?

Roger L. Costello initiated an interesting discussion (on, 01-Dec-08) on xml-dev mailing list, about following concept:

I am exploring the idea of "do all application coding in the XML languages."

Here is a response from a colleague:

"... in general XSLT is cool but limited. If your transform requires any "higher math" or advanced functionality or external code libraries (such as geometry coordinate system libraries), you almost always have to go back to a higher level language (such as Java) at some point."

Does my colleague make a true or false statement?

XML professionals on the list expressed interesting opinions about this. Following is the link to this threaded discussion, http://lists.xml.org/archives/xml-dev/200812/msg00007.html.

Just thought of sharing this with readers of this blog (if you got a chance to visit here).