Those "requirements" are the ones I listed in my other post; i.e. adventures to discover what you need and obtain it, proficiency in a tool or arcana, money, and time.
Again, no checks required.
(Emphasis mine.) So, you figure an adventure to get X and Y will not contain checks to recognize X and Y? I mean, failure is supposed to be an option on an adventure, right? And players are expected to actually think about how they approach adventures for their own success, right? We aren't just having them walk int eh door, and hand them the thing they want tied up in a bow...
How do you know what you have is a working recipe for a magic item? How do you know it is a recipe for the item you want? How does your unskilled fighter come away with confidence that he's getting a +1 sword, and not cinnamon raisin scones, or a Dagger of Self Stabbing? Same for ingredients - how do you know what you've got in your hand is powdered catoblepas horn, and not cornstarch?
By all means, enter into the making of magic items without the skill - but do note that you are apt to come out with fewer +1 swords, and more "sword stuck into what appears to be concreted oatmeal" than your more fully skilled colleagues.