This is exactly right. I've been in all three roles and all three are essential to success.
I can also relate to the notion that the engineers do all the work, which was a sentiment I shared early in my career before I understood the kinds of problems executives and founders had to solve. I cringe when I hear an executive say "How hard can it be? Get some bright bulbs in here and have code up a solution that doesn't have these problems." or when an engineer says "The CEO just parties with 'investors' and blows sunshine up our ass while we actually build the thing he is gets credit for." or when a founder says "I wrote the foundation this company at a dam hackathon in 24 hours and you're going to take 6 months to have an alpha release?"
I have seen again and again that people who haven't been in the role they are criticizing have constructed an understanding of it that doesn't capture what the actual role entails. Or in the the crowd funding case completely under estimating to cost or effort to do some aspect of development they have never done before.
If the company is hitting its milestones, people know what they should be doing, and the problems that pop up all seem that they can be overcome. Then you know all three classes of people are doing their jobs well.
When things take forever to get done, nobody knows why or how the thing they are working on fits in, and every week there is a new problem that changes all the priorities and efforts, then you know you're on the way to being dead as a company.