The linked article does a poor job of convincing skeptics, it only looked at nominal rates, not effective rates, and additionally confused the issue by looking at the first derivative of the top marginal rate. Finally, it didn’t even fix the marginal rate to an exchange-rate fixed income ceiling across countries.

Sloppy methodology with a conclusion in search of evidence.

To the extent that people are motivated to make money the prospect of making less of it reduces their motivation.