As discussed in the article, this is a very different kind of ion thruster. That category is quite large. In particular, I believe essentially all ion thrusters flown have been electrostatic ion thrusters, including both Deep Space 1 and the Hall thrusters discussed in the article.
They all need a propellant and power feed. But, you can use those same feeds for an array of multiple engines. Thus, 'scaling up' has a wide range of options and trade-offs. Vasimr let's you scale power output a lot from the same engine, but so would an array of smaller engines.
With that in mind the specific techniques are important, but the gaps are often overstated.
With that in mind the specific techniques are important, but the gaps are often overstated.