The steam curing is probably needed for strength. Concrete always cracks as it cures – there’s no way to completely stop ALL cracking. If it develops large cracks, the concrete will be weak, but if it only develops micro cracks that you can’t even see, it will be MUCH stronger. One of the ways you can minimize cracking is by keeping the concrete wet while it cures. That’s why when they pour concrete driveways, it’s best to keep misting water on them for a day or two. It will increase the strength of the concrete tremendously. Another way to minimize cracking is to keep it the same temperature all over the concrete. And since the center will get quite hot (concrete makes its own heat as it cures), they use heat to keep the outside from cooling off too quickly.
