Well I meant several things with that claim, which is why, per the theme of the thread, you cannot summarise these matters in cute sentences.

Fire is only possible in an atmosphere with extraordinarily high accumulations of oxygen on planets with an atmosphere, etc. The only known process to bring this about, as far as I know, is life.

Generically, lighting is the 'original' fire on earth. But I take it the commentor was thinking more in their school days of the sustained sort of burning commonly called 'fire'.

While oxygen is the most common oxidizer, it's entirely possible to have combustion without it. Such as utilizing halogens.