In fact, ironically enough, the feature of Follow-Up questions was removed in 2010, and is now (2017) reported to be in A/B testing:
- Quora as Eternal Recurrence: The history of the first iteration of Follow-Up Questions by Nick Nicholas on The Insurgency
- The mammoth was revived for a reason by Nick Nicholas on The Insurgency
The irony is, I suspect this question is being asked in the context of the recent removal of Question Details (Changes to further emphasize canonical questions by Sumi Kim on Quora Product Updates). The reintroduction of Follow-Up questions after 7 years is plausibly connected to the removal of Question Details, as the second linked post speculates (based on a connection made by Dot McHale).
, Quora Admin Emeritus