Question

I didn’t find any documentation as to why XPath support was dropped from jQuery.

Answer 1

Read this: http://ejohn.org/blog/xpath-overnight/

I should, also, probably answer the inevitable question: “Why doesn’t
jQuery have an XPath CSS Selector implementation?” For now, my answer
is: I don’t want two selector implementations – it makes the code base
significantly harder to maintain, increases the number of possible
cross-browser bugs, and drastically increases the filesize of the
resulting download. That being said, I’m strongly evaluating XPath for
some troublesome selectors that could, potentially, provide some big
performance wins to the end user. In the meantime, we’ve focused on
optimizing the actual selectors that most people use (which are poorly
represented in speed tests like SlickSpeed) but we hope to rectify in
the future.