I used Orkut in the early days (from 2004 - 2008). The growth trajectory was similar to facebook. All the elite colleges in India were using it in the beginning and then it rapidly spread across other colleges.

But the thing was:

1. There was no News feed. You had to actually visit your friend's wall to make a comment/see what they were up-to.

2. That other person would know the next day that you visited their profile. This discourages people from taking interest in the lives of others. You didn't want to come across as a creep or having nothing better to do with your time.

3. Communities/Forums were a big thing. There wasn't too much to do so you visited "communities". It became a turf war between Indians, Brazilians and a few other countries over content. So if you were from another country, you would get the feeling of not belonging here. I always thought that it drove people from other countries away.

4. Facebook created a personal bubble/universe centered around you. Discussions on forums/pages were not a high priority. News feed was the game changer. I remember people moving away en masse from Orkut to Facebook around 2007 - 08.