The VRM world is rapidly changing with the introduction of pure digital controllers. We have seen them working for awhile now, but several companies have been working on these types of controllers. Chil has been absorbed by IR? DigiVRM is an IR product, but branded for ASUS. Same goes with Giga's Dr.MOS, IRS makes these. NCP makes a lot of VRs for Nvidia and Intel Server side. TI, MAX, OnSemi, and a bunch of other companies are backing out or introducing unique lineups, that include the inductor and capacitance.
This all started around the time Intel realized that VRMs were causing issues with their CPUs. None of the top companies that created these ICs wanted to get involved in trying a new technology and trying to sell millions of units to Dell/HP/ASUS...etc. So Intel created the VRM12 Spec that would initiate a need to move from the try and true analog VRMs to Digital VRMs. Once this change initiated, other companies started to become involved, those that had a stronger history in digital power rather than analog. Companies like TI had been born and raised in Analog, but NCP is somewhat of a new player (but they were bought by OnSemi).
Once VRM12 became the standard, all the major motherboard companies decided to start creating their own digital power circuit to attract customers. VRM12 came in right when UEFI became the standard, so basically we can think of the motherboard receiving a huge facelift. And this created a domino effect for all the ICs you see on the motherboard. Just about all of your ICs (including the VRMs and BIOS) communicate with each other using I2C/SMBus or something related to these protocols. Digital ICs communicating on a common bus allows for a high degree of configuration, and this circles back to OEM companies wanting their own VRMs. Specific features could be integrated that is only seen on their boards. Not exactly how things have turned out, but we are in 2nd/3rd generation of these types of motherboards, so a lot can still change.
With digital VRMs, sampling speeds have increased, this means that all the components on the power rails can be examined individually to a higher degree. We can see the ripples of capacitors causing overshoot and undershoot to occur, falsely tripping the OCV and UCV. We can also drive FETs faster! Lets say you wanted to build an ePower board, well this would be very difficult to achieve these days unless you buy in bulk. Thats because these newer components are made to reduce the issues just stated. The inductors provide a silky smooth current, and have little power dissipation. The capacitors are made of better materials to create a tighter tolerance and reduce ripple. The gates of FETs are fast (0.5ns to 2ns), but the capacitance due to the thin large surface area gate, is very very low (very important for driving FETs at fast speeds!).
All in all, it comes down to OEMs protecting their new power rails. They want to make it more difficult for others to obtain the same performance. Because in reality, these circuits are super simple, and do not change much. A resistor here or there to create different tolerances, thats it. The same inductor size and capacitance will be there for just about each generation. The materials in these components is the key though.