2048 exploded because anyone could modify it, create a doge version, create an AI version, a multiplayer version, an inverted version ...
And they did. The formula was ridiculously simple, so it was easy to do.
You can't do that with Threes. It's proprietary. You can't take it apart. You can't mess around with it. The only thing you can do with it is play Threes.
My son has 2048 on his Ipod without me mentioning it to him, and he never ever gave one hoot about being able to modify it.
The same can't be said for Three's, because there is greater resistance in spreading it and people trying it out. First, I probably wouldn't have tried Threes. Second, I wouldn't have been able to link it easily to people who might have been partially interested in it. Third, the variants and mods were what kept people coming back.
Giving an example is a perfectly valid way to make a point. Circumstantial doesn't mean wrong.