Funny you mention that. Growing up, I remember watching the Transformers cartoon, and begging for the toys. Years later, I watched a retrospective program on the series, where they noted that The first episode was just a long form advert, and was so popular, they ordered a series, of toy commercials.

So nothing is totally new here, except that the average youtuber seems to have no ethicical qualms about pushing any product, while networks did, and still do, qualify their advertisers.