I would say the way steroids build muscle more easily is via reducing recovery. The person you present would get that benefit, be able to train more frequently

I would say the way steroids build muscle more easily is via reducing recovery. The person you present would get that benefit, be able to train more frequently and grow faster than a person doing the exact same things except not taking steriods. Steroids also allow one to exceed their genetic strength maximum, but unless you're already banging up against that wall (say 10-15 years of sustained excellent programming, diet, & rest; and maybe half that if taking steroids the whole time) their benefit is almost entirely speeding recovery time.