There is one major myth in modern linguistics which is responsible more than anything else for the discipline losing contact with its subject matter, the study of languages. It goes as follows. There are essentially two types of linguist. The descriptivists, who do field work and write grammars. And the 'theoreticians' (i.e. the formalists, people working on non-basic theories) who do not gather data themselves but rather interpret it, from the point of view of their chosen formalism. The myth is that the work done by the 'theoreticians' is more difficult, more important, more intellectual, altogether on a higher plane than the basic work undertaken by the descriptivists.
This is wrong, from every angle. First of all, every person who describes a languages is also a theoretician; they have to be, to make any analytic deductions. Every point in a grammatical description is a theoretical statement, and must be justified by appropriate argumentation.