What do you think @1muflon1?

@Jp_ I basically agree with @TanYongBoon. Also, in your argument there would not be any growth because of that forgetting. For example, lets say for a sake of argument that without marketing a product would be valued at 20e with marketing at 30e so the additional value of marketing is 10e. Well if you assume that people forget the old marketing that means its value also disappears.

When you take that 20e product with 10e extra value of marketing then that marketing value should disappear and then re-branded products without marketing would have 20e and with marketing 30e again.

For marketing to lead to growth it would have to manage to continiously increase value of the products - for example product still has value just 20 but in first year marketing adds 10e value in second year 20e value (so total value is 40) third year 30e (so total value is 60). Also, this should happen because of marketing itself not because marketing becomes more efficient thanks to technology and new development in behavioral research and so on.

Of course, with current technology marketing firm can produce more valuable marketing campaign then a firm in 1990, thanks to internet, computers, machine learning etc. - but then its not really the marketing but technology like Solow-Swan model predicts