Also, most early forms of technology tend to be dangerous to the user (and anybody nearby, on occasion). Early cannons for instance had a tendency to explode and kill their users (which is where the phrase "hoist upon their own petard" came from, a petard being a form of early cannon) and the first aircraft weren't exactly sturdy or well-built. In that sense, I could totally understand early steam armor being both powerful and dangerous to use, as they hadn't quite figured out how to work out the kinks yet.