For feature films, the jobs are specialised, so Houdini does tend to be restricted to FX (although more and more companies base their lighting/rendering pipelin

For feature films, the jobs are specialised, so Houdini does tend to be restricted to FX (although more and more companies base their lighting/rendering pipeline on it). But for commercials, it can happen that it is used in more departments. I did commercials where animators where taught to use it, and that was a success in my opinion. They were happy because the animation tools are basically the same and the rigs were updated faster than they would be on other packages. And it is true I've rarely seen models being done in Houdini. The only time I did one was for this commercial (https://vimeo.com/17808406 https://vimeo.com/17808406), where the character is quite procedural. Had it been a more classical character, a Maya modeller would have done it.