Well, I could argue that by inviting a comparison between trusting a single fact from Wikipedia and trusting arbitrary generated output, you are practicing less critical thinking than you otherwise might.

The example's not relevant; the two things are not analogous. Moreover your point only works if one accepts your conclusion that:

    Independent verification is the main way they measured critical thinking

But they also reported assessing things about the content, like style/personality, logical soundness, relevance to a topic, or suitability for a specific purpose.

Studies don't need to justify themselves with concrete conclusions; gathering the data for future use is a fine goal.