I'm going by what was stated in the movie - "An Adventure in Space and Time", where in the dramatization the head producer states that they wanted a show that appealed to young men and children - who weren't watching tv that much and into sports. (I remember, because I rewound twice when they said that - and thought whoa that's the same demo Marvel Agents of Shield went after, word for word.)

Now it was a fictional movie - it's possible they embellished.