Small teams don't need complex project management, they need effective project communication.
At the beginning, it was project management: it was basically a science, with its own specialised vocabulary and wide range of software options to actually apply that science. This science included contracts, budgeting, very refined task, sub task, sub-sub task breakdown, dependencies, complex graphs, time estimates, etc. A few people, the "project managers", were masters at finding their way in this little jungle of terms, rules, and methods.