Well, online marketing is indeed growing. It is also true that the reach of digital marketing is far more than that of offline marketing. Also, the majority of consumers can be found on digital platforms.
Say, for example, if you are a small shop owner of stationery and you wish to reach the masses, you cannot do so by offline marketing. Even if you think to apply, the option is door-to-door marketing which is time-consuming and expensive.
On the other hand, making a business page on social media or creating a website can increase your reach to potential buyers quicker. So yes, digital marketing definitely has an edge over offline marketing.