[alwaysbeconsing]

Does sound rightfully terrible. It's exceptionally common cognitive mistake to discover a categorization (of people) and take it as prescriptive rather than descriptive. Especially in corporate business context.

Have not read the book, but the Four Teams list obviously describe real roles. But that doesn't mean organization must or should go out and immeiately partition their teams according this scheme. The value is to recognize that these roles exist and are probably performed somewhere by someone in some way or another in the organization. (But perhaps your org is too small to have much of Platform component, say, so it's just Alice who update CI every N week on as-needed basis.) And to use that knowledge to understand the overall process and where there may be problems or future problems.