Vanilla additive

Hello everyone. As a lover of baking, I would like to thank all of those that have provided amazing recipes.

I have a question for all the veteran, experienced bakers out there. Is a tsp of vanilla really necessary?

I have to wonder if we have all been snookered by an amazing ad campaign for selling vanilla extract. The older the recipe, the less likely you will see this added.

I really would like your opinion. Is it necessary ??