Exactly. If reviews are part of the process, then they're someone's job. Either someone isn't doing their job or management hasn't made it clear what their job is. Both have easy solutions.
However if you have strong collaborators it's not necessary to intervene.
Basically competitive people identify their utility function and start working towards maximizing that. You need someone with authority to define their payoff matrix, making it explicit that they are required to collaborate to "win".
