Marketing works by convincing people that they need the thing you are selling. It’s just as effective with something people don’t really need as with something they genuinely do need. Take for instance ‘Conditioner’ for your washing. Conditioner comprises gloopy long chain molecules that adhere to the fibres in the clothes, they also act as a substrate to bind volatile chemicals (perfume) to them.
So you wash your clothes to get them clean, the machine rinses out the residues of the washing powder to ensure that the clothes are clean and then you add conditioner; more chemicals that are not able to be rinsed off. They also don’t rinse off all the rubber and plastic components in the washing machine since they are designed to stick to fibres which are chemical similar to the plastic. The conditioner that’s left hanging around in the washing machine acts as a substrate for growing mould, reducing the useful life of your washing machine. Mould spores in the washing machine and hence your washing can’t be healthy for you either.
Conditioner is advertised as making you towels bouncier and softer and more perfumed. It does that by sticking to the fibres. It also has the side effect of making the towels less absorbent and less effective at drying you. Since the washing powder was perfumed the extra perfume in the conditioner is redundant.
Conditioner is an unnecessary pollutant with little to no useful purpose and a whole bunch of negative impacts including adverse impacts on the environment.
But the advertising has convinced almost everyone that it’s a necessity.