Solar thermal collectors that can boil water have existed for decades. You don't need concentration for that, simply use a black absorber plate with pipes under a glass plate and put a vacuum between the absorber and the glass. Selective absorbers or glasses will improve the efficiency.
There are two problems with it: The generated steam will have a low temperature not much above boiling water. Most industrial applications need process steam of a much higher temperature (although there are some exceptions).
There are also problems with the two-phase flow of the steam-water mixture in the pipes, which is generally unstable and difficult to control. Technically it is much easier to concentrate sunlight, use an oil with a high boiling point as the carrier liquid and use it to generate the steam in a seperate unit.