Oh puhleazze, stop treating me like Petrino in Albany. That is not what I said and you know it. Pashto and Dari are the official languages of Afghanistan, however there are at least 26 other languages spoken there. Arabic, Kurdish, Assyrian, Turkmen, Armenian are among the languages spoken in Iraq, but there are certainly more. I'm sure Farsi is common to both countries to some extent.
That really isn't the issue. The fact is that there were plenty of Arabic speaking members of Al Qaeda in Afghanistan. Many linguists who might know Uzbek or Pashto might also know Arabic or Farsi. There was, and still is, a shortage of linguists in these languages who can also hold clearances. It is common sense that if you move most of these assets from Afghanistan to Iraq that the prosecution of Al Qaeda in Afghanistan will suffer.
There are many factors that allowed Al Qaeda to grow. Bin Laden making world wide contacts during the Afghan struggle against the Soviets, the abject corruption by the ruling families in most Arabic countries and in Saudi Arabia in particular, the Saudi decision to rely on western forces to counter Saddam in Gulf War I instead of embracing Bin Laden's proposals, the Saudi refusal to confront the Bin Laden situation, the Palestinian/Israeli issue, the presance of Western forces in Saudi Arabia throughout the 90s and Clinton's refusal to try to kill the bastard even if it meant collateral damage or mistakes were made were among them. Trying to kill Bin Laden and his top lieutenants with extreme prejudice was not a strategy that allowed Al Qaeda to grow.