Left thumb placement

I've just recently joined and have only viewed a handful of videos. I did see something about moving your left thumb so as to fret with your fingertips. My question is this: is fretting with your fingertip more important than keeping your wrist in a neutral position? After 5 years of learning guitar I still haven't gotten any clarity on this issue. Any help would be greatly appreciated

Ok, given the lack of replies, I'll just hold the guitar in a way that is comfortable for me, without any regard as to whether it's technically sound. If there is one thing I've learned, it's that some aspects of playing this particular instrument are they way they are because that is the most comfortable way that player can do it

Thumb placement changes based on what you need to do Mark. Sometimes its directly behind the neck, sometimes it wraps over muting the 6th string. This will all make sense the more you practice.