According to some estimates, brands are expected to spend $15bn on influencer marketing by 2022. But media reports also indicate that the influence of influencers in marketing circles could be waning. A brief look at the issues involved:   Influencer marketing: origins and after About a decade ago when blogging was popular, automobile brands would first reveal details of a new model to that community instead of a traditional mass media ad. Even prior to that, Sunsilk from…