The example you gave is not a referral. People sharing coupon codes do not receive compensation (other than a warm fuzzy feeling). Spam wise it's pretty innocuous - people share their code once and move on. even those asking for a code generally do so once and move on. It's hardly a 'cesspool'.
A referral situation would be entirely different. People will jockey to get their code/key front and center to maximize views and they'll do all they can to entice sign ups (including compensating people for using their key). The higher the reward the worse this situation becomes. The admins have indicated they're open to the idea of revisiting this rule, but it has to be done with careful thought and consideration. Speaking as a user, it's also easy to understand why they also have to take into consideration the financial impact this could have, however small. That's just good governance.
For what it's worth I'm in favour of relaxing the rules but not until the rules are clearly defined and everyone agrees to play fair.
Don't talk about it, be about it