Q. Why does Rubinius not support frozen and tainted? A. Rubinius has better features; frozen and tainted are considered harmful. To elaborate... Both frozen and tainted depend on strewing checks throughout the source code. As a classic weak-link system, only one of those checks needs to be misplaced for the guarantees offered by either to fail. Since the number of checks is high, and as new code is written new checks need to be considered, the features inherently constitute unbounded complexity and unbounded risk.