I don't know much about working in a team, that's sure. But isn't the implementation of one pure function the responsibility of one or just a very few workers? When does a worker need to read someone else's implementation of a pure function? I can imagine that but definitely not on a daily basis, and not in a scale that concerns the whole team.
By pure functions I mean pure functions, that are mathematical functions/algorithms for example, and that are obviously properly unit tested, etc.
You go to war with the code base you have not the code base you want.