Comment Re:There is already a safe subset of C++ (Score 1) 72
Closed world is like ethe transmission in a traditional car. All of the parts are created to exacting standards and fit together only one way. Transmissions are not user serviceable. Any modifications to the transmission likely degrade its functionality.
People can and do service their own transmissions, in particular doing a fluid and filter change is generally a pretty easy job. There are also modifications and upgrades to transmissions. You can buy "built" transmissions which include heavy duty parts which can handle larger power, torque, and/or shock loads than stock ones. There are "kits" of aftermarket parts which either address wear over time or even correct design deficiencies like either lazy or excessive engagement of clutches.