A few days ago I remarked on Twitter: "sad that Contributor, a great alternative to ads/tracking, is owned & marketed by Google, which has more to lose than gain from promoting it"[0]
The idea behind Contributor is a powerful one: one that if aggressively marketed and expanded, could (at least conceivably) provide a viable hybrid model for online content publishing (that could coexist with ad-tech).
But Google is a one-trick pony (with ads, obviously) and has everything at stake here. That makes Contributor feel like more of a defensive "moat" initiative -- there to passively discourage others from pursuing (or investing in) similar ideas. Maybe I'm being too cynical. I too am happily subscribed to Contributor--the most dramatic difference is The Next Web -- where the crazy canvas-flying ads are toggled off.
[0] - https://twitter.com/spencenow/status/646480765794975744