What work do you want to do?
By suggesting you don’t need project managers, you’re saying that you, an engineer, want to do this work and my question is, “Do you or do you not want to be an engineer?”
That's the question Michael Lopp asks software engineers who resist including a project manager. Replace engineer with designer or developer and I'd ask this question to most small digital agencies and many a busy freelancer. Even if you have only have a few people on a team, someone has to do the work of project management, which means less time to work on that which they are truly great. And I'd go so far to say that you are under-serving the client by not dedicating a resource whose primarily responsible for ensuring a great client experience.