The first TV commercials were anchors reading text. It's not that first TV stations thought this would be particularly effective ad format for the television, but they had no choice. The reach of the first TV stations was very limited and neither advertisers nor TV stations were willing to spend money on new ad formats tailored specifically for the television. TV stations nonetheless wanted to earn some advertising dollars so they asked their corporate cousins, that is, radio stations, to pass some of their advertising to them and they effectively treated television as just another radio station. Only much later native ad formats were developed and accepted by advertisers that fully exploited the visual nature of the television, not just its audio part.
In many ways the history of web advertising is a replay of the television story. At first everybody treated web as a digital reincarnation of newspapers and only much later services native to the web have come about, such as Facebook and other social networks. Just like early television stations, first web publishers were little cousins of big news publishers and they effectively took advertising from the bigger analog cousins and pasted it on their web pages. Eventually, standard formats emerged and locked the publishers in the confines of medium rectangles, skyscrapers, and other banner ads formats. But with reduced revenue and one step from extinction, publishers are now forced to find more effective ad formats for their online efforts that would be more engaging to their readership. I'm pretty sure that in a decade or two some native ads will pop up that will define Internet generation as profoundly as this and this television commercials defined us, the television generation.