I'd heard the Michelin story repeated a couple of times by a friend, and it sort of checks out. The Michelin Guide was originally more a general guide for French motorists in 1900, to increase said demand for driving and therefore their tires, although when the restaurant section became more popular, they started hiring anonymous reviewers in the 20s and then eventually awarding stars about 30 years after the initial publication.

1 star : "A very good restaurant in its category" (Une très bonne table dans sa catégorie) 2 stars : "Excellent cooking, worth a detour" (Table excellente, mérite un détour) 3 stars : "Exceptional cuisine, worth a special journey" (Une des meilleures tables, vaut le voyage)

So it's not as if it was a masterminded plan, a decent marketing tool just sort of evolved into a restaurant reviewing guide.