I don't know any industrial actuator that will benefit from being driven with 18 bits of precision. Are you sure that the industrial world needs this?

Using isolated supplies will help obtaining the 18Bits of resolution at the output but you will most likely loose many bits when connecting it to a real world apparatus.

Usually, high precision is done by closing the loop of the control using a high precision A/D. While the precision of the D/A is important, not much gain is seen pass 12 bits when controlling a valve or a motor. The friction, noise, temperature and other effects become dominant.

Of course, if you are aiming at nuclear phisics application where a million $ actuator is used, you might use 18 bits.

It all depends on the application.

Industrial sensing now requires ppm level precision and accuracy and is one reason to go for these. Industry does what research needs and they go hand in hand. I am in industry for research and my needs are of same level that research scientists asks for. I do have a research facility.

Yes, there are many industrial areas that do not require such precision. However, i specialize in this area.