Rakeback programs is really hard to maintain. Essentially they are almost impossible to keep up.
I think, its more about the fact,
poker sites are realising, that they dont have much reason to reward the most active players. The most active players are usually professional or semi-professional players, who are often winning / net withdrawing players. But what keeps the whole wheel turning is the losing / net depositing players. And they typically dont benefit from loyalty programs like a traditional rakeback system, because they tend to only play now and then.
This is why, we are increasingly seeing traditional rakeback being replaced by incentives, which reward people for depositing. Or for logging on every day like a daily spin of the wheel of fortune or a daily challenge, which can be completed in a few houndred
hands.
PokerStars have gone even further than this and actually raise the bar for collecting their already meager chests, if you "play to much". Then suddenly you no longer need say 1.400 points for a certain chest but 4.500 points. Its "tailored to the individual player", as they say. Which basically mean, they dont want to give money back to people, who are already beating the game.