Twilio Segment migrated from 140+ microservices back to a monolithic architecture after microservices created unsustainable operational overhead. The team consolidated separate repos and queues into a single service with a unified test suite using Traffic Recorder. This transition dramatically improved developer productivity (46% more library improvements), reduced deployment complexity from 140+ services to one, and simplified scaling. While accepting trade-offs like reduced fault isolation and less effective in-memory caching, the monolith proved more suitable for their server-side destinations pipeline.