@chjara You're probably correct that using the term is a PR win, but it wasn't originally coined for that purpose.

Natural gas is natural because it's naturally occuring in the ground rather than synthesized. It's not accurate to call it methane, as even though most of it is methane it's not pure. It's a useful term, just as "air" is useful for something that is mostly nitrogen.

The Swedish academy records the first occurrence of "naturgas" in 1903. The term is almost a century older than the term "greenwashing" and anyone even talking about doing anything about climate change.