Zoro can do no touching and used it to prevent King from stealing his swords:
Flame aura, haki tendrils, etc. whatever you want to call it, the massive overflow of Ryuo is kinda specific to Zoro.
And besides, Zoro was able to hurt Kaido significantly even before he awakened Haoshoku while Luffy needed Haoshoku coating to do real damage against Kaido.