It takes a skilled interviewer to deal with and evaluate that level of nuance on the fly. It's much easier to scale an interview process with checklists.
Did they ever confirm this experimentally, or it is just speculation about how it should work? It does seem like spike protein traveling further through the body than we thought it would would explain this.
In college, my economics professor put a question on the final about how we might solve the economic issues around the corn blight in Malawi. At the time, I wouldn't have dared raise this as the answer.