About 15 years ago, they started something called Brigadization, trying to replace a division with a brigade; mainly taking a division, subtract 2 combat regiments out, and let the remaining regiment keep half of the division's logistics BUT they kept the taskings the same. What they learned was that no single re-enforced regiment can do the job of 3 regiments no matter how well supplied it was. They eventually was forced back to division. The poor brigade HQ was overtasked and had insufficient supplies to do the job of a division.
Simple math didn't even occurred to the PLA. If you taking half the supplies away and cut two thirds of your combat power, you're going to do less than half of what the division used to do.
A quick look at any of the Cat A Group Armies (and they are Group Armies, not Corps) showed that none of the divisions are in a position to take the artillery, engineering, service brigades. Simply put, a re-enforced division is not going to do the job of an army.
Correction: About 25 years ago. This was the 90s.