Depends on how you look at it, H370 boards have either more or equal VRM then their budget Z370, better IR units and better heatsinks .
Aorus h370 to Z370 Aorus 7, the H370 has a newer MOSFET which allows it to run cooler, there for less need for a lot of them to spread the power/heatload .
Asus and Aorus flagship X470 use the same new IR model then Taichi which is 14+2 Vs 10+2 of the others. Asus and Aorus do use different controllers , but Taichi and Aorus use the same controller
So it's vendor using newer/better VRM but at a lower count .
Those 3 boards are interesting as you've got parts which is used by some but different mixture .
Normally Gigabyte Gaming 9/SoC are the boards with the highest amount of VRMs on any board, 22 on z170 series ... Don't think we'll see that commercially and if z390 Aorus 9.. don't think the VRM count will be any higher - just better