Steam turbines are subject to much less heat than gas turbines. Are you aware of the difference between how combined gas cycle turbines and steam turbines function? In a coal plant, coal is burned to heat water into steam which turns a steam turbine to rotate a dynamo. In a combined gas cycle plant, gas burns in a gas turbine to rotate a dynamo. Then the gas turbine exhaust is used to boil steam to turn a steam turbine to rotate a dynamo.
Gas turbines are subject to much greater heat than steam turbines. Without advanced metallurgy, the turbine blades would melt. There's a reason why the steam turbines were first used in earnest in the 1890s while gas turbines didn't get used extensively until the 1930s and 40s.
What about this is confusing? Combined cycle plants require gas turbines to build. The term gas turbine exclusively refers to turbines burning gas (or gasoline if "gas turbine" is being used to refer to gasoline turbines) to generate an impulse. Plants that burn natural gas to heat a boiler don't use gas turbines, they exclusively use steam turbines. Gas turbines (both the gasoline and natural gas kind) are complex to fabricate and few countries have the technical ability to manufacture large and efficient turbines needed in combined cycle plants.
> Which costs more and makes them dependent on foreign countries for energy production. Hence why they choose coal.
This makes no sense. Perhaps you aren't aware that coal power plants universally generate electricity using steam turbines? Do you think they're using pistons like an old steam locomotive?
> But these articles' optimism is contradicted by the actions of the countries in question. They're building coal plants.
Well, no. I mean, Indonesia is, but India isn't, and China isn't, and the articles claim that Vietnam is rapidly ceasing to. And politicians' choices often have explanations that go beyond maximizing profit.