Something That Seems To Quiet All Debunkers

Simple question:

Could you please explain to me why a terrorist would plant evidence to incriminate themselves?

http://www.newyorker.com/fact/content/?011008fa_FACT

QUOTE
Many of the investigators believe that some of the initial clues that were uncovered about the terrorists' identities and preparations, such as flight manuals, were meant to be found. A former high-level intelligence official told me, "Whatever trail was left was left deliberately—for the F.B.I. to chase."
"Oh, What a tangled web we weave, when we wish to decieve."

FOR CONTEXT, please see:

  • "Let's discuss the 9/11 hijackers"
    valis.cjb.cc/hijackers.html
  • "Or were there hijackers?" - A rebuttal
    valis.cjb.cc/hijackers4.html

  • Hijacker clues were "meant to be found"

    Can anyone provide a rational expanation for the above?