Some people said it was cheating. Some said you'd never get better if you used contrast paints. Some just loved the art of using opaque paints and the discipline of the process.
Now people mix and match, and even some pros use them in scenarios where they make sense. Many other companies produce similar style paints.
At events, especially tournaments, it's led to much nicer armies to fight against.
Thankfully they don't consume huge amounts of water.
This post isn't about paints.