Why do we use article before Auxiliary

Tenzin, can you give an example that raises this question or expand further on your question ?

Definite articles precede nouns, and do not immediately precede verbs. 

You may be confusing direct object pronouns and definite articles. Same words, different meaning and function. 

 Using le, la, l', les before nouns when generalising (definite articles)

 Using le/la/l'/les = it/him/her/them (French Direct Object Pronouns)