An other very famous dictionary is "Le petit Larousse". As a native French speaker, I look into the dictionary for definitions of course, but also often to check spelling.

Native users do use dictionaries. When asked to read novels by Balzac or Zola, they need dictionaries, of course... For students aged 14 or older, the "Petit Robert" is indeed the dictionary most often used in French-speaking countries.

Native speakers rarely use dictionaries (they already know the words for daily life). They use them as needed. For example, for school work. Le Petit Robert is a famous, good French dictionary for adults. There are other, simplified dictionaries for non-native French speakers. The Larousse Student French-English dictionary has common vocabulary and an example sentence for each word.