The idea of having the separate boards isn't to restrict folks to one or the other, it's more to set an expectation.
If someone posts on the "New To Poly" board and doesn't have their terminology straight or does the DADT, or OPP or UH type stuff, then it's important to treat them with more respect and go slowly.
Having that in another board means that those folks who don't want to deal with that side of things can stay away and not be irritated by them.
"Listen, or your tongue will make you deaf." - Native American Proverb