When we developed Axapta back in the mid-90es in Denmark, we created the DAT company as a way for single-company entities to have a restricted usage of 1 vs. multiple companies. It was extension of the old XAL concepts (actually came from a product that retired under the name 'C4', really...)
But nowadays, what is the real purpose? There is no global data stored in there - it is instead stored in multiple companies (through Cross Company Data Sharing Policies) or in global tables (that don't have a dataAreaId field.
I'm probably only going to get speculations as it would require a MSFT engineer with insight into the company data structure (like MFP, for example - Michael, if you're reading this, by all means pitch in). But I'm really curious as to what it's even there for.
Customers find it confusing and I can't blame then.
Thoughts?