This isn't a good argument for mob programming imo. This argument pretends as if the only reason programmers would ever work individually (or in pairs) is because more keys can be mashed in less time.
In reality, we work individually (or in pairs) so that work can be completed asynchronously. I can fix a UI defect while Jim fixes a performance issue, and Sue adds a new feature being requested by a potential client.
Having worked on a large team, and being an introvert - mob programming would have been a disaster. We had one or two extroverted personalities on the team, and they would have driven the entire effort while the majority sat and watched.
It's really cool that this works for someone. Great teams adapt and find a process that works. However, I would advise leadership at any company doing mob programming to carefully observe the more introverted personalities on the team. They probably won't say anything, but they might be dusting off their resume.