The busienss drivers of this request are many.
1. We'd like our account team members to be able to send out personalized emails w/o having to create seperate mailers for each and every one of them, which is what you need to do because Marketo cannot see SFDC account team objects.
2. We'd also like to have account team membership available for internal marketing reporting purposes and alerts. Again, as the account team objects are not visible to Marketo, we need to do a lot of manual work.