History of mobility!

For drivers, that information was essential. Gas stations did not yet exist, so drivers needed to know which pharmacies sold gasoline in several-liter containers. Motorists needed the timetables that listed when the sun set during the year, because highways did not yet have lights. Only a fraction of auto repair shops stayed open all year, which made it crucial to know which closed at the end of summer. Details like this distinguished the Michelin Guide from the tour books of the time, which assumed that people traveled by rail. 

The Michelin brothers’ efforts to make driving easier extended beyond the guide. Once company employees began rating hotels, they made clear to hoteliers that they should offer free parking. They also lobbied the government to put up road signs for motorists—Edouard Michelin is sometimes credited with inventing road numbers, because he convinced the government to enlarge the numbers it painted on highway posts. At times, company men put up road signs themselves.

Similarly, a major aim of Michelin marketing was to promote the car as a way of life. "With a car, no more 5 a.m trains," a Michelin ad in 1924 declared. "With a car, there is more opportunity for the pleasant things in family life."

It was like a combination of Yelp and Google Maps. 

Do people still use Yelp? Google offers all that information under Google Now (or whatever it is called but those cards are useful while traveling)

Yes a lot of people still use Yelp and a lot of Google's info comes from Yelp. 

A guide of the rubber chicken circuit?

:)

At the time, groundbreaking.  

So why do they do it now? Legacy?

I guess so.  They pioneered and evolved and earned the status.

Is it still popular in an era of smartphones?

The ratings mean something.

The pressure of maintaining Michelin three-star status (their highest rating) and the possibility that he might lose it were blamed by some for Loiseau’s suicide. True, there were other factors—he suffered from depression, was overworked, and was mired in debt—but in point of fact he had actually told Jacques Lameloise, then chef-owner of the three-star Maison Lameloise, “If I lose a star, I’ll kill myself.” Loiseau “was so scared of Michelin,” says Daniel Boulud, a good friend of Loiseau’s who is now the celebrated chef-owner of Daniel in Manhattan. “There was gossip that he was going to lose his star, and I think he was devastated by the idea of that. He couldn’t cope with the pressure.”

http://www.vanityfair.com/culture/2015/09/top-chefs-michelin-stars

That does sound like a lot of pressure.