In the case of Grok's turbines, no emissions controls means sick people. Plus all the CO2 pushing climate collapse faster which hurts every coming generation.
Gas plants are not bad… but imagine 400 MW of gas plants in a concentrated area. You’ll always have NOx and SOx by products whenever you’re burning gas.
Gas is certainly less of a problem than coal, but they still produce plenty of bad stuff: nitrogen oxides and bad VOCs like formaldehyde that are well studied to increase risk of asthma and some types of cancer. I certainly wouldn’t want to live close to one.
Coal plants are bad.