Appropriate equity investment segmentation

recall the case of “chinese robotics industry” from the textbook p158, why the geographic and economic activity approaches are not the best choice here? according to the solution, as is explained " …given the similar geographic and industry composition of the chinese robotics industry"
why cant we just categorize all chinese robotic starups into the same groups??
thx

P156 says the geography approach is typically based on the stage of markets’ macroeconomic development and wealth. Common geographic categories are developed, emerging and frontier markets. In this case, the Chinese robotics industry is specified. The manager wants to identify appropriate company stocks in this industry that experiencing rapidly accelerating earnings. Thus, you should choose an approach that could reflect the earnings growth.