In my time at $bigCorp, I saw the title “principal engineer” used to describe two positions simultaneously, and sometimes both in the same org;

- the good, hands-on, full-of-wisdom senior engineers, whose relevant experience and strong vision enable an entire floor of developers to build the right stuff and quickly. These guys made commits to high and low level code, from network debugging to interpreter design. Really inspiring people.

- The toxic “ideas guy” “architects” who believe it is their job to write white-papers on how everything should be, without providing any guidance on how to actually get there. They believe that all problems would be solved if only we had the right perspective, even though perspective can’t be executed on x86 architecture. These guys constantly made me wonder why they were there and what they did all day.

Sometimes the architecture is not designed by a single person. Sometimes it is a group. Sometimes it evolves from every-developer-does-it. Sometimes the role switches quickly from person to person. I don't know scientific studies to compare the approaches. Usually everbody just agrees that ideally one person should do it all.

It is usually easy to identify architectural decisions. You can then find out who made that decision and thus figure out who is the architect.

For example, in a web project: Who decided to build microservices vs a monolith? Who chose the database technology (PostgreSQL vs MySQL vs MongoDB vs ...)? Who chose the cloud platform? Who introduces external SaaS products? Who split up the big thing into pieces for different teams?