But the "wannabe professionals" will make a pretty wide audience aware of the traditional roots from which they take their style, however commercial - they have to eat don't they! So from that audience, there will come a few more who are interested enough to perform traditional songs, and may even write new songs to become part of the tradition in the future.
I agree there when considering the BRITISH folk scene. Without folk song as a "community" experience the first introduction for most people will be from commercial sources. In my young days this was The Spinners or Bob Dylan.