No it is not absolutely necessary
By just using oil and cooking with it, you will over time "Season" the pan. It's just not a great way of doing it
You will get better results following the basic steps documented on SA or elsewhere e.g. What's the best way to season a cast iron skillet?
Basically all you need to do is; clean the pan, oil it, heat it to a high heat. That's not too tricky, is it?
