I think WP editing can be a good idea, but one has to accept that the payoff is not going to arrive anytime soon. I don't think I started noticing much impact from my NGE or Star Wars or other editing projects for years, though I eventually did begin noticing places where authors were clearly being influenced by my work (or in some cases, bordering on plagiarism). It's entirely viable to do similar work off Wikipedia - my own website is quite 'evergreen' in terms of traffic.

This sort of long-term implicit payoff makes it hard to evaluate. I don't believe the results of this survey help much in evaluating WP contributions because I am skeptical people are able to meaningfully recall their WP usage or the causal impact on their beliefs. I bet that if one dumped respondents' browser histories, one would find higher usage rates. One might need to try to measure the causal impact in some more direct way. I think I've seen over the years a few experiments along this line in use of scientific publications or external databases: for example, one could randomly select particular papers or concepts, insert them into Wikipedia as appropriate, and look for impacts on subsequent citations or Google search trends. Just as HN referrals underestimates the traffic impact of getting to the front page of HN, WP pageviews may underestimate (or overestimate) impact of WP edits.