Seems we somehow missed posting this FLIP into the forums here when we published it a few weeks ago, so catching up and apologies for the miss here.
TL;DR - the model where integrators have only REST and gRPC endpoints which need ongoing polling has a number of down sides and limits options considerably for builders. Events are increasingly important in dapp development and so it is proposed that we support push-based event streaming to provide better options for builders and improve network scalability. It is our hope that FLIP-73 sets the foundations for more diverse and varied ways to integrate with Flow which are better suited to certain use-cases or builders.
We would love your feedback on the FLIP and look forward to hearing from you all!