Vortechs aren't for everyone. For one, they are super expensive. Two, some people dont need that much power/ variability. If your running a tank with mostly Lps
and softies, you're not going to need something that can make literal waves in the tank. Koralias are nice because you don't have as much power with a single ph, they are relatively cheap, and you get more control with more ph's. You could make the argument that you can have more than one mp10 running low and get the same control, but the price scares most people away.
Vortechs are great, but the price doesn't justify them for most people and with koralias, I sure dont see the need for them in a tank like dary's.