Why do they have to be severed though?

If you work on the Severed Floor (MDR), you don't really know what you are doing, or why. Just looking for "scary numbers" and trying to hit your quotas.

It would make sense for Lumon to insist upon severed employees if they were dealing with high-level secret information, and the company was afraid you might leak those secrets.

But what's the worst that could happen if a never-severed employee worked in MDR? "Hi Honey, I'm home. Moved around some numbers today for some unknown reason."

Is it really necessary (from an upper-management perspective) for a MDR employee to have a lack of awareness of their day-to-day work when they go home at night?