A possible reason for drinking while cooking is to cleanse the palate. That is, when I'm prepairing a meal, I often taste and adjust the seasonings of the various dishes being made. And often, I'm tasting wildly different flavors in quick succession. It is well known that alcohol brings out the flavor in certain herbs and spices. So a bit of it rolling around on the tongue may enhance a chef's ability to taste his/her creations and adjust more accurately.
For me, I use milk to cleanse my palate. I find it clean, and with a taste that doesn't linger in my mouth, making me ready to taste whatever it is that I need to tate next. I also am fond of a bottle of ice water when I'm cooking. Far fewer calories, but it takes more to clean out existing flavors.
I neve drink alcoholic beverages, personal choice, but can understand the logic of some chef's using them while cooking. Of course, if the alcohol is a crutch, or used to reduce stress, then the cook is merely diminishing his/her skill level while drinking. Certainly, alcohol frees teh reactive brain while putting asleep the part of the brain that helps us manage our impulsive side. This may allow some to try new things more willingly, especially if they are unsure of themselves. But again, to me, that's just a crutch and isn't really helping, but rather hurting them in the long run.
And yes, I am a very analytical personailty. You'll just have to put up with me, 'cause I can't seem to change that part of my personality.
Seeeeeeya; Goodweed of the North