Collaboration is not the same as averaging opinions.
Strong software design benefits from disagreement. It needs people to evaluate assumptions, expose missing constraints, and challenge preferences that masquerade as principles.
Design-by-committee often does something weaker: it smooths out the uncomfortable edge where a decision lives. The result is a design that offends nobody because it commits to nothing.
Responsibilities blur. Naming gets vague. Tough decisions deferred. Accountability disappears.
Healthy collaboration keeps accountability visible. Collaborative rigor defends against challenges, survives pressure testing and changing business requirements. Decisions made must explain tradeoffs plainly enough so future maintainers can understand and avoid mistakes already addressed.
Design by committee is an anti-pattern.