> So what is the point in artificially creating a test situation where the student is isolated from resources she'll have at her disposal in real life?

I can envision many scenarios where a person needs to be quick on their feet and does not have time to look things up. Drivers, pilots, doctors, etc. Certification provides a lot of value to society.

The other point of testing is to separate wheat from chaff. To see if someone is disciplined enough to learn the material or see a task through. There are issues of going beyond the ideal amount of testing here, but not totally useless in my opinion.