How has e-marketing become an integral (important) part of marketing in today's society?

People are using the internet more than ever. New apps are coming out everyday and people are using them. Instagram is a great app do market/promote on because so many people are using it. You could post an ad on a streetlight and the exact same add on Instagram and the sales between the two would be very different. Social media and internet is a commonly used thing. With so many people on it, someone will see what you're marketing and want it.

E-Marketing=Home shopping, saving time, discounts. Who hates this?