A successful team is a team, with roles, not a random collection. Obviously any project will involve different technical specialties. Some people are better at

A successful team is a team, with roles, not a random collection. Obviously any project will involve different technical specialties. Some people are better at early design and core coding, others at filling out that skeleton, still others at debugging or testing or things that enable either. Your most productive programmer is very unlikely to be great at leadership or even mentoring - which are themselves not quite the same thing. You need people who are enthusiastic about every new technology and people who would rather stick with the tried and true. You need all sorts of balance along with the psychological safety that allows people to be different and have disagreements without losing trust in one another. I've seen "superstar" teams absolutely fail, and "journeyman" teams absolutely fly, strongly correlated with whether management understood what "team" means.