I've been on large projects where we didn't have one such person but was nevertheless very successful. The key there was that one qualified representative for

I've been on large projects where we didn't have one such person but was nevertheless very successful. The key there was that one qualified representative for each part of the affected organization and other relevant parties in the core team, and there were frequent alignment meetings where they were all present. The representatives were close to the action, not some three-levels-removed manager. In the meetings processes and such would get discussed step by step in detail, and any representative could chime in at any point to say "this won't work" or similar. Hard to do though, and quite costly in terms of organizational resources required.