Most portal enquiries are one line: is this still available. Answer it in thirty seconds and you have a conversation. Answer it in three hours and they have already toured something else with whoever replied.
The second problem is sorting. A large share of enquiries are browsers, tyre-kickers, or people who are eleven months from moving. Agents burn their day discovering which is which, one call at a time.
Iris is doing the sorting, not the selling. It answers the availability question, establishes timeline, price band, whether they are pre-approved and whether they already have an agent, then books the ones worth an agent's hour.