I don't know anybody who plays The Sims and hasn't filled their game with user-created furniture, clothes, hair and even eye colours. And I know a lot of Sims players. The Sims community, much like the Spore community, is positively bursting at the seams with stuff like that.
I conclude that the writer of that blog has done very little research, or just knows very little about their subject matter.
The point is the Sims community wouldn't have been so huge if the initial content wasn't so great.
And how does that explain Spore's even bigger community?
In fact, a lot of what that blogger said is spewing directly from their ass. They say IGN reviewed it negatively, and yet IGN gave it three Best of 2008 awards. They say Spore was a failure, but don't give any facts to back it up, other than the fact that they felt it lacked content. Despite the fact that the game ships with hundreds of creatures, vehicles, buildings and so on created by Maxis themselves. It is, in fact, possible to play the game without EVER seeing any user-created content.