It's probably a good strategy, but Hacker News is a bubble and most people aren't going to do this absent a very hard limit in the app itself (like Path did).
App-based limits/nudges are all but certainly the only way to see widespread adoption. But the tactic arises naturally out of both attention scarcity and the tendency for high-salience (or high-appeal) messages to be widely distributed regardless.
More problematic is when you're searching for needles in haystacks / nuggets of gold: sparse signal in high-noise environments.
