It’s clearly not a good idea to setup expectations regarding all those capabilities on a single person (the tech lead).
The article just asserts this without even making a case. I would counter that a lot of these capabilities require an overlapping skillset (in particular an overall familiarity with the codebase and a general awareness of the wider technology landscape), such that it’s probably cheaper for one or two people to acquire all of them than to try to spread them around the team. Mediator/concierge/ambassador are almost the same role with different names. I’m all for carving pieces off the tech lead role as the role expands beyond one person’s capabilities, but much as all successful microservice systems are built monolith-first with microservices carved out as and when that makes sense (and usually the component that was the “original” monolith remains indefinitely as the core of the system), I would build a team tech-lead-first and carve out responsibilities as and when it makes sense to do so.