1/ This is a great question. In my experience, it's largely because product tends to operate "inside-out" (test and learn, adjust course frequently) and marketing tends to operate "outside-in" (commit to a broad timeline and narrative, then build into it) https://twitter.com/TheHonorableAT/status/1298309051072339972

2/ I've seen this create a lot of tension where product distrusts marketing because "they want us to commit to deadlines WAY too far in advance" and marketing distrusts product because "they won't tell us what they need to tell us in order for us to plan and execute our work."

3/ In a lot of cases, this is a miscommunication issue. Marketing usually doesn't want to have a *detailed release plan* 6 months in advance. They want to know, broadly, what story they will be able to tell their customers about the product and how it will help them.

4/ I've generally found it helpful to have a direct, upfront, facilitated conversation between product and marketing about this very question: "What is the story we want to tell our customers when we reach [marketing milestone]?"

5/ After that, set up some regular checkpoints to touch base. Make sure marketing sees the product evolve, and product sees the narrative evolve.

6/ As with so many "team x doesn't trust team y" problems, working in the open is key here. Product teams that try to "protect" their roadmaps and internal documents from marketers are setting on crash course towards "WAIT THAT'S NOT WHAT I THOUGHT WE WERE DOING"

7/ This is the point I was aiming to make in my MarTech East keynote last year: if "Agile marketing" just means recreating Agile ceremonies within a siloed marketing function, it isn't going to accomplish anything:

8/ Going back to @TheHonorableAT's original question, I think the reasons people actively *maintain* these silos are primarily that 1) Breaking them down presents an enormous, messy communication challenge and 2) NOT breaking them down leaves you with a GREAT, evergreen excuse.