Just as I believe that many software teams should use lock rarely or never, I also understand that for some, lock is a critical feature. A great example is a team building a game with lots of graphical assets kept under version control along with the code. With binary files and other cases where automerge cannot work, locking a file is often the right way to go.

For somewhat obvious reasons, there isn’t much support for lock in distributed version control. When the system is designed to provide excellent support for offline usage, a feature which requires online usage is not likely to get much focus. Unless and until DVCS tools provide support for lock, gaming companies are probably going to stay with centralized tools.