Starting to enforce Developer Certificate of Origin (DCO) for (some) ROS 2 repos

In the linked post @gerkey doesn’t give a rationale, it contains merely a statement of intent:

We’re also working on updates to developer policies, such as enforcement of a Developer Certificate of Origin (DCO) on contributions to core ROS 2 repositories.

In ROS 2 TSC Meeting Minutes: July 24th, 2018 it’s also only stated that DCO will be required. ROS 2 TSC Meeting Minutes: September 6th, 2018 states “Explain rationale, say that we’ll take comments now and at ROSCon”.

It’s probably obvious, but could you perhaps provide some insight into the reasoning behind this decision?

I’ve probably missed it, so if there was any discussion at ROSCon about enforcing DCOs, my apologies.