[elevation]

> purpose built systems

You can see the benefits and limitations of this approach by considering commodities where "purpose built" is economical.

One common purpose built device is the dumb gigabit network switch. It has a well defined and stable specification, and for performance reasons the switching fabric is implemented in a dedicated ASIC which cannot be reprogrammed or remotely disabled. This makes it very stable and difficult to attack directly.

The limitation is that this rock-solid infrastructure only shifts the attack surface to a higher layer in the stack. The same switch that can't be attacked directly will happily deliver an email that tricks a human into assisting a hacker's scheme, like installing a virus onto their accounting PC.

Sure, you could implement your accounting software in an ASIC as well, but unfortunately, the requirements upon accounting change much more frequently than the gigabit 64b/66b waveform spec; if the government is allowed to issue new regulations then it will always be more economical to build the accounting system on a general purpose machine.

[dbuder]

Your gigabit network switch runs Linux. Even the securities exchanges' gigabit switches run Linux (on a FPGA).