It depends on your engineers really. If you have great team, who enjoys, uses or deeply understand the product and VALUES their craft then no you do not. Howev

It depends on your engineers really. If you have great team, who enjoys, uses or deeply understand the product and VALUES their craft then no you do not. However you have to empower this team with a larger degree of control than most organizations are willing to give. Product people need to come with goals, not products and hash out a way to get there with the engineers... Just because a product person wants to build "X" doesn't mean it is going meet the goal in the most cost effective way, and a good engineer might suggest something else to get to the goal that saves time and effort when it comes to building and running whatever the feature is that is being suggested.