the reason people recommend against vacuuming a PC
A regular vacuum isn't doing anything with ions or high voltages. Moving air can generate potentially harmful static electricity, but usually the reason people recommend against vacuuming a PC is because if you spin the fans doing that, the motors inside turn into generators and drive current back into your PC parts that could damage them.
I don't think you two are even contradicting each other. The airflow going through the base can be 15x smaller than the total result, but also require more energy than just using a regular fan that moves that amount of air.
Total airflow and efficiency are two independent things.
Disclaimer: I have no real data on how Dyson fans work.