Because that's like saying anybody can bake a cake because you have all the ingredients and the oven.
But unfortunately, that's not the case. You you need to know the measurements, and the order of mixing the ingredients, and how to mix them, along with temperature and cooking time, or you won't have a very good cake.
Like one time, this old roommate of mine decided to bake a cake. She had all the ingredients, tools, and oven. She even had a recipe. But she had never baked a cake before. She didn't understand that some of the ingredients, getting the proportions right, is vital, and she put 4 teaspoons of salt in the batter instead of a 1/4 teaspoon, because she misread the recipe. The cake came out flat and hard, and she didn't understand why. If you're a baker, you would never do that, even if you saw a recipe that said 4 teaspoons of salt, because you'd know that was a typo, as every baker knows too much salt will make your baked goods not rise, and in-fact, is why many bakers use "unsalted butter" because they want their salt measurements very precise, and to come out nice and fluffy. However, she assumed since there's lots of batter, and it was just four teaspoons, how it could make the cake literally come out like a brick. I had to explain, that salt, is not like flour. If you put 4 teaspoons too much of flour in the batter, it's not a big change, but even just a little too much salt, can mean the difference between having a nice cake or an unappetizing inedible one.