never make users do work that machines can easily do
Why haven’t list features on Facebook and/or Twitter caught on? – Quora
Because they are manual and require people to do work. People hate to do work, especially when it’s upfront work for some possible future benefit.
To use a not too far off example: consider the success of Mint. A big part of it was that it automatically categorized transactions for you. It’s not perfect by any means, but it’s good enough. If they left categorizing up to the user, I don’t think it would have been as successful.
Exactly why the conversationlist idea occurred to me as soon as I saw Twitter lists in action: find ways for machines to take over the care and feeding.
It really surprised me that people who stopped updating their blogrolls after a couple of months didn’t see a bump in the road looming for Twitter list usage.