1 gallon of gas contains 33.7 kWh of energy. [1]
The average ICE car goes 24 miles on 1 gallon of gas. That's 0.7 miles per kWh (24/33.7 ≅ 0.7).
The Tesla Model 3 goes about 4.1 miles per kWh. That's 5.8x further per kWh, or 5.8x more efficient!
Most of the difference is because ICE engines are inefficient. They waste energy. Just like the article says. :)
The point made by the article about the source of electricity from power plants was simply that EVs are more efficient even when charged from coal fired power plants! Your point about the "ICE in some power plant somewhere" is temporarily true... as the grid de-carbonizes there will be fewer and fewer emissions from grid-scale generation. (Nuclear + renewables is my personal guess for where we're headed.)
It's kind of sad that several threads here are playing devil's advocate. Unless some dramatically better tech takes the world by storm in the next 2-3 years, EVs are going to completely take over the market. Economies of scale should dramatically drive down costs over the next 5-10 years, and then all new cars will be EVs. No one will want the old, expensive, dirty, loud ICE cars. And this is really good news for everybody!
[1] https://www3.epa.gov/otaq/gvg/learn-more-fuels.htm
[2] https://afdc.energy.gov/data/10310
[3] https://ecocostsavings.com/electric-car-kwh-per-mile-list/