XHTML1: What's wrong with -- in script/style?

Dear HTML Working Group,

  Appendix C.4 of the XHTML 1.0 Second Edition Recommendation states

[...]
  Use external style sheets if your style sheet uses < or & or ]]> or
  --. Use external scripts if your script uses < or & or ]]> or --.
[...]

I do not understand what the problem with -- in those elements is, as
far as I can tell, there is no difference for e.g.

  <style ...>/*--*/</style>

or

  <p style="/*--*/">...</p>

in HTML versus XHTML, the specification seems thus in error in this
regard.

regards.