I don't think they had any patents protecting them, etc.
Agreed. Pownce and FriendFeed were both hailed as Twitter competitors in the early days. In 2008 Twitter was consistently plagued by downtime as they had trouble scaling. However, the service was simple and easy to use and they did a great job getting early digital influencers and celebs onboard evangelizing the platform. When Twitter first got started they also had a suggested user list and recommended lots of famous people and digital influencers to follow. This created a bit of a self-fulfilling prophesy - those on the list would evangelize twitter helping to funnel even more people in and boosting their own popularity, etc.