I think there's a time and place for discouragement. Some people just weren't born to write. It's seldom that you'll find someone with NO talent in writing, but just like there's people you really wish wouldn't sing, there's some people you really wish wouldn't write.
While I wouldn't discourage someone from writing ever, I
would discourage them from seeking publication before they learned to write properly. Chances are they'll reach untold levels of frustration before they figure out it isn't their ideas that are being turned down, but their blind eye to grammar and diction.
But don't be discouraged if people are discouraging you! Take their criticism as a challenge! Clean up the areas they're slamming you on and then mention them in the foreword of your first best selling novel!!! Muahahahahah!!!
"Thanks to that jerk who told me I couldn't write, I'll mail you a signed copy of my book."
