Because a lot of people are „experts“ in how a country should be run. Like we‘re all master soccer trainers when the worldcup starts.
The fact that a country might lose export or gdp numbers due to its drastic clean air measures is like fingers on a chalk board for these people.
The fact that these numbers are meaningless just shows we‘re all brainwashed to be nice little worker bees and care for our masters wealth more than our own air.
Its the same when a person with 30k yearly income says taxing the rich is bad.