Can a team of experienced, empowered developers successfully design the architecture of a product? Sure.
Can a team of experienced, empowered developers successfully design the architecture of a product without a unified vision of how the architecture should be structured to accomplish its purpose? Probably not.
Can a team of experienced, empowered developers successfully design the architecture of a product while staying within the bounds of their role as developers? Absolutely not.
A lot of ink, both physical and virtual, has been spilled arguing over the utility of architecture and architects. A common misunderstanding among the anti-architect faction is that an application is the sum of its parts. This is particularly prevalent with those espousing the view that if the team does the “simplest thing that could possibly work”, the architecture will just emerge. To be honest, an architecture will emerge from this method. Whether that architecture is coherent, performant, scalable, secure, etc. is quite another matter.
In order to have an informed opinion on whether or not a particular role is need, it is necessary to understand the nature of that role. For example, while the ability to code is a critical qualification for both application and solution architects, it is not the sole qualification. While architects are concerned with the structure of the code, that structure is a means to meet the needs of a customer, not the end in itself.
The purpose of an architect is to understand the needs of the stakeholders and meld his/her knowledge of code, platform (OS, database and web server, etc.), and environment (machines and network) into a cohesive whole that accomplishes the mission. This means the architect’s focus must be on the product as whole, not just a particular project or release and also not on just one aspect (code) of the product. The evolution of both code and platform (hardware, supporting software, and network) needs to be managed across the lifecycle of the product in order for it to remain useful.
For smaller products and teams, it may well be possible for the team to undertake the tasks listed above in addition to their duties as developers. As the scale of the product grows, however, dealing with multiple levels of abstraction and achieving timely consensus across multiple feature teams becomes problematic. At this point, coordination and specialization becomes more important. The architect role then becomes responsible for collaboratively developing and maintaining a unified high-level vision, providing sufficient guidance to keep the product coherent as it evolves while avoiding the trap of Big Design Up Front.
Whether the role is fulfilled by an individual or multiple individuals or the entire team as whole is less important than whether the role is handled effectively. Both “Whiteboard Architecture” and the classic “Big Ball of Mud” need to be avoided.