Why Lances? The mounted Dismount with a Lance only functions if the other person is wielding a Lance as well. It used to function on anyone, but they nerfed if by making it only work on other Lance-wielding foes, and so it's been relegated to RP Jousts only now.
After AoS launched, i would stealth up near to people in Fel on my Stealth Fencer (back when you had to count your steps), hop on my Ethy while hidden, then come bursting out of the shadows with Lance equipped, dismount them, then switch to a War Fork and Disarm+Bleed them, and kill them. They couldn't run (me mounted, them dismounted on foot), they couldn't fight back (disarmed), and they couldn't cast spells (Bleed ticks along with my fork hits would interrupt like mad).