A good architect is one who leads by example, and without a good understanding of the technology stack and business domain, an architect is not equipped to deliver the pre-requisite outcomes for the enterprise. The team members typically have deep-dive expertise in the specific technology areas but will lack confidence in the architect if he is not competent with in the domain or technology.
The architect is the bridge between the technology and the business team, and hence he/she must understand all aspects of the technology stack to be able to liaise with the business team. The architect must be conversant in the business domain in order to drive the team and all the stakeholders toward a common organizational goal. An architect might not be busy all the time, but he/she leverages decades of expertise to solve and monitor the organizational IT landscape, making quick decisions during various stages of the SDLC. The project manager handles the people management aspects, freeing the architect of the hassles of operational tasks.
An excellent architect is pretty much a hands-on person and should be able to mentor members of the design and implementation teams. He/she should be knowledgeable and competent to handle any complex situation.
An architect's success in interviews does not come easily. One has to spend hours prior to each interview, wading through various books and references for preparation. The motivation for this book was to consolidate all this information into a single reference guide that will save time prior to interviews and can be a ready reference for important topics that need to be revised before the interviews.