This is true even today as the ISAF captures Haqqani Network commanders on a regular basis and their attacks do not let up. Keep this in mind when the discussion about Taliban commanders comes up as there is always someone to take charge when a commander is killed or captured.
Here is something you do not hear about everyday because Hamas and the Palestinian Authority have actually gone after al-Qaeda pretty hard in their territories. Apparently a Palestinian al-Qaeda member got himself killed in Afghanistan. I wonder if he counted as one of just a few hundred remaining al-Qaeda members remaining in the Af/Pak theater (Sarc).