This is not true. When you are at the peak of the decarboxylation curve I posted, you will be converting THC to CBN faster then THCA to THC. So by decarboxylating before baking, you WILL be creating sleeping cookies
I'd suggest a low baking temperature recipe.
Also, creating the butter, also decarbs it. So you will have very little THC left in there, and a LOT of CBN.
Decarboxylation, or decarbing, is a function of heat. So everything heating up the product, will decarb. Using that graph I posted, you can see if it is at all needed, and when making butter AND baking with it, you do not need to. High CBN gives a more sedative effect.
What happens in decarbing is that you convert THCa to THC, this normally happens during smoking or vaping. At the same time it converts CBDa to CBD. AND THC to CBN .. but at a slow rate .. untill most of the THCA has become THC, then THC to CBN speeds up.
Knowing this, you can aim for a certain kind of high in your edible, using that graph and adding times of processing/baking.