Because I can concentrate on the song and the recording process.I have got the best mics,top level engineers, all that I have got to is cut the track.The track is cut totally dry-sterile,no effects nothing.The less complicated the better.You are baking the cake,the icing comes on later,to really run a good guitar sound you must be compressed and pre-amped.This pays off in spades,it is impossible to boost a weak frequency,there is nothing to boost.The mics and their placement is huge,I must have the best.And then you hand it to your producer giving them total control,to qualify as my producer you must have already mastered being an engineer.You must know the shortcuts.I am an executive producer,my job is to bring the concept to life from the embryo,from the acoustic demo to the finished master.The producer is in charge of the sessions with total control yet I overide that.Until I sign off on it the project is not finished.