Matthew O'Riordan, co-founder of Ably, discusses common challenges faced by fantasy sports and live events app developers, focusing on solutions for realtime data delivery. Ably, a realtime data delivery platform, has gained traction among fantasy app developers who often encounter problems such as scaling live updates to an unknown number of users, maintaining data synchronization, and handling upstream gameplay events. To address these, O'Riordan suggests using the Pub/Sub pattern for scalable asynchronous data distribution, Serial JSON Patches and CRDTs for efficient and consistent data synchronization, and message queues for managing upstream events without compromising system performance. Ably's offerings, including its Pub/Sub feature and message queues, provide scalable and reliable solutions for these challenges by ensuring data integrity, efficient bandwidth usage, and fault tolerance, allowing developers to build robust realtime applications.