While I doubt you will find steel frames as stiff in the bottom bracket and had tube as the stiffest new carbon bikes, modern frame design in all frame materials, including steel, has evolved to being much stiffer than the old frames. My Bridgestone RB-1 had more bottom bracket sway than my Salsa Casseroll and way more than my Roubaix, but it handled great and I climbed a lot of mountains on it.