I never noticed that you couldn't.
There's no real harm in letting people post there in my opinion. Other people may even spot errors that the guide writer may not.
Because you don't do it all at once, you have to slowly transition. When you stock your fridge full of greens and healthy shit, it's going to seem intimidating, and odds are that you will revert back to your old habits.
Start by having a bowl of grapes once or twice a day or drinking water instead of unhealthy beverages.