Plasma is well known for scaling, but its real brilliance lies in state minimization. It significantly cuts down the data that everyone on Ethereum needs to store forever.
Instead of cluttering the main chain with every game move or micro-transaction, @Plasma keeps these activities on a separate chain. Ethereum only retains a small, periodic cryptographic checkpoint a single hash that represents the entire sidechain's state.
This keeps Ethereum's "state" its ever-growing ledger lean and manageable. Nodes do not have to store the history of every app; they only keep the compressed proofs of their integrity. Plasma is not just moving computations off-chain; it is also systematically cleaning up the leftover data, protecting Ethereum's decentralization and node health for the long run.