"This creates a lottery effect where posters know that they could get $50 for something as simple as posting a link to answer questions from a new user. Often they don't see anything, but occasionally they get a big bump and that makes all the difference."

Consider my lottery proposal https://steemit.com/steem/@liondani/lottery-rewards-every-24-hours-for-10-lucky-curators I think it will work better than you tipping "randomly" ... Because many will thing you are not "objective" with tipping at some point of time... They will not blame the blockchain...