Horizontal sharding for MySQL made easy allows developers to scale their databases linearly by partitioning data across multiple servers, each with an identical schema, reducing the workload and making it possible to keep data on a single server at an optimal size. This approach contrasts with vertical scaling, which involves increasing hardware resources to improve speed and capacity, but can lead to overprovisioning and inefficiencies. Horizontal sharding offers several benefits, including improved performance, cost savings, and reduced operational complexity. Companies like YouTube, Slack, JD.com, and Hubspot have successfully implemented horizontal sharding using tools like Vitess and PlanetScale, which provide a managed database platform for accessing the power of Vitess without requiring extensive expertise or risk.