Word of mouth is the most effective marketing. Ask any marketer. However, as profiteering discouraged folks that made the effort to come here, the effect of that marketing was to discourage new users by those discouraged relating their complaints about how things were here. That's very effective, just not at bringing new people here, as we see.
All the changes HF21 brings are percentage changes. How do you achieve qualitative evolution with quantitative changes? All the complaints the one million or so users that were chased off had are being increased. I don't believe anyone expects anything different from what's going to happen as a result of making people less welcome here than they were when one million were chased off.
You don't have to bang your head on a brick wall 21 times to realize it hurts, and how to stop hurting yourself.
RE: Open Letter to all Steemians - Hardfork 21: Culture Change