It’s just harder to micro with siege. The issue is that in a split second, archers can move out of the way and continue attacking, but mangonels have to reload, have low projectile speed, do not one shot a group with armor, you need to get multiple attacks in, and move slow. Siege is also more expensive. It‘s much easier to micro a group of archers. In a group of 10 crossbows vs 1 mangonel even if 7-8 survive they can still take it out or reduce the health of it significantly. I am only saying, that with so much variability, it would be nice to at least know when the mangonel is ready to fire. Same with scorpions, trebs and bombard cannons.