In his keynote at RailsConf 2018, Mark Imbriaco explores the theme of scalability in technology, specifically addressing common misconceptions about Ruby on Rails and how it handles growth. He begins by introducing himself and sharing that the title "Rails Doesn't Scale" is intended as clickbait to stimulate discussion. Imbriaco distinguishes between performance and scalability, explaining that performance relates to the speed of individual requests, while scalability involves how well a system can handle increased load by adding more resources.

Key points discussed include:
- The Concept of Scalability: Imbriaco underscores that scalability often gets misinterpreted. Linear scalability suggests that by adding resources, system performance will double proportionately. He debunks the myth that Rails inherently lacks scalability, encouraging the audience to consider architectural choices over the framework itself.
- Socio-Technical Systems: He emphasizes the importance of the social aspect accompanying technical systems, suggesting that understanding both elements is crucial to effective scaling. This "socio-technical system" includes users, developers, and administrators, which he argues contribute more significantly to scaling than mere technical design.
- Personal Journey and Learning: Imbriaco shares anecdotes from his career, including his first encounter with programming languages like Perl and Ruby, and the pivotal moments that led him to Rails. His narrative includes worked experiences at companies like 37 Signals and Heroku, where he learned valuable lessons about building collaborative cultures.
- Community Sharing: One major takeaway is the idea that community is a critical resource that enhances scalability. When individuals share knowledge and experience, it produces a multiplicative effect on growth rather than a linear one. He encourages developers to contribute actively, as this can exponentially amplify the community’s capabilities.
- Lessons from Failure: He reflects on his entrepreneurship experience, stressing the need for careful management of workloads and responsibilities to prevent burnout, mentioning personal experiences that serve as cautionary tales.

In conclusion, Imbriaco argues that people are the driving force behind scalability, not just technology. The key takeaway is that engaging with the tech community and sharing knowledge amplifies the growth potential of systems, ultimately enabling a far greater impact on technology development and implementation than technology alone could achieve.