I don't think that is just a "commercial" problem. Inside KOffice we have several groups like corporate or non-coporate developers but also the teams for the individual applications. Every group tries to find a set of rules that works for them. For example the Krita team doesn't have a strict review process and everyone can commit, reviews are only done if someone feels that it needs a review. In general this has been worked very good for the Krita team. On the other hand we have a quite strict review process on things like flake. Of course this causes problem when the different development models clash.
 

- our release schedule does not fit with Nokia's, let's create a branch so they can continue to develop features.
  Yes it's open source and nobody can force anybody to work on something he is not interrested in. But then, why do we bother with a release schedule and freeze periods,.... In my mind, those things are there because it is good practice in the community to try to concentrate your time and effort during these periods at solving problems. Nobody forces you to, but then again, nobody forces you to leave your seat in the bus to the old person, it is just something you do.

Same problem here. Different groups want different schedules. Inside KOffice we have a big imbalance of development power and application readiness. Inside the Krita team we sometimes wished to have our own schedule, but we are bound to the KOffice one. We have to accept that we can't all move at the same speed, so branches are a necessary evil.