The way we do our hair or make-up alters regularly, but it's unlikely that the stuff in our make-up bag mutates so conspicuously. Cosmetic colours vary, formulas improve, but – generically speaking – the products themselves remain the same.
The appearance of a new one is, then, pretty remarkable. Not that there is anything novel about what's in the bottle – oils have been around as long as life itself. But cleansing skin and hair with them feels like a radical development, or here in the West anyway. Other cultures have never forgotten their gentle, balancing benefits (in Japan and India, for example, they're the norm), but oil of all kinds has long hovered on the border of our distaste – one of cleansing's aims being precisely to eliminate it.
Beauty's current flirtation with oils may be part of a broader shift in sensibility. Just as the fat-free dietary ideal of the past few decades has waned in recognition of nourishing, "good" fats, we're accepting the wisdom of feeding skin with what it naturally contains.