Wow, spot on.
The issue was that the team was being pulled from pillar to post and could never focus on anything for more than 5 minutes before having a different highest priority task foisted onto them, requiring them to change focus immediately and abandon progress.
By forcing a roadmap I gave the dev teams a week or so to work on something a little more undisturbed before moving onto the next thing. This massively increased our throughput and the quality of the outcome, but it was not popular with the founders because it forced the founders to crystallise ideas and prioritise them properly for the resources we had.