Misquoting Quotes

Ignorance is bliss. Wisdom is blisters.

Nostalgia was never what it used to be.

Deleuze and Guattari have been totally misunderstood because the following has been wrenched from context: "Forming grammatically correct sentences is for the normal individual the prerequisite for any submission to social laws. No one is supposed to be ignorant of grammaticality; those who are belong in special institutions. The unity of language is fundamentally political." (112)They are NOT advocating for this sort of prescriptive approach to language; rather, they are describing the social system around language--how language is a political tool. Why persist in quoting them as though they are promoting some sort of linguistic purity?