From my blissful ignorance I wonder; even then wouldn't it still be a role very dependent on previously established guidelines compared to their live-action counterpart? I mean, all the material has to be created beforehand, be it a composite with bi-dimensional elements or pure CGI three-dimensional environment to work with, so much of the scenes have to be devised on early stages for the director of photography to have enough material to finalize its work on. For it, having this person in question to contribute efficiently and early on its input and actively with the rest of the staff to avoid having to rework on specific parts, to achieve an intended result.
That leaves a necessary previous (and more obvious) consensus from said staff (directors, story-boarders, animation directors, etc.) on how the scene has to be tackled from the beginning, in a much more evident way than a equal live-action professional for a similar work (with real actors) would do. Seems like more restricted in general, with less freedom and inspiration. I think that what raito-kun says could hint more to a blurring of the lines between those specific staff positions because of the previous background the mentioned people have, that helps them to do it in that way.
I think what you say here is very true, and it has been something I have been pointing out for a while now. I feel that with a production like Fate/Zero it is a lot more of a team effort than something which can be easily distilled down to the responsibility of one person, which is why some people feel uncomfortable at calling it a sakuga anime.
For many of the scenes in the series which stand out a lot, you cannot really say that one particular person is responsible for the majority of the sequence like you can with animated scenes by Nakamura or Matsumoto. Instead it would be a mix of careful storyboarding and direction, in some cases possibly with consultation with the photography team, good modeling, animation, and effects for a CG element - like for example Berserker, and the final composite being able to put everything together well as originally planned.
Now, having said that, there is a very talented and relatively new animator at Ufotable who is directly responsible for the "action animation" of Berserker in particular. His name is Masayuki Kunihiro. He was responsible for planning the action animation for Berserker in episode 5, as well as the aerial action animation in episode 14. For ep14 he is actually credited as the Special Effects Director for the episode.
But can we consider this sakuga in the traditional sense? I do not believe so, because I feel this is similar to how Takeshi Koike was responsible for being the action animation design in the Gungrave videogame. They tapped on his experience as a traditional animator to help plan poses and keyframing for how the characters would move and attack, and used that to create the realtime 3D animation for the game.
In this case, Kunihiro clearly plans out the Berserker animation sequences in terms of how he would pose, move, and attack, as well as the missile circus motions and so on, but none of that reflected as actual animation frames in the end product. Another comparison would be Imaishi's involved in Black Rock Shooter, where he and Akira Amemiya both storyboarded and directed the CG sequences, which are then fully realized by the CG and photography team.
I think this new hybrid form of anime is pretty exciting, and while it is very different from how traditional anime is made, it is still something refreshing and new, and represents a new generation of visual artists.