The feature part of it is to allow JS code in a browser sandbox to compute stuff faster. Possibly even render it. The explicit anti-feature is the ability to d

The feature part of it is to allow JS code in a browser sandbox to compute stuff faster. Possibly even render it. The explicit anti-feature is the ability to do yet another side-channel attack. Also out-of-spec is the incredibly power-inefficient IPC mechanism. And I doubt a probabilistic querying of what kind of code the rest of the system is running was ever part of the spec either.