A lesson I learned the hard way is that you either FORCE Fetch a dog, or you don't. If you go through it just 'hard' enough to teach HOLD, FETCH, and GIVE, then you aren't FORCE Fetching the dog. You are just teaching new commands. While under cetain conditions this might suffice if you have a dog with exceptional drive, there WILL more than likely be an occasion when the dog will refuse a retrieve. It could be a big old mean gander with nothing but a broken wing, it could be the greenhead that is next in line after that gander, or it could be a canvasback floating feet-up 20 yards in front of the blind when it is 5 degrees and the ice is thick. The option to refuse is there, and valid for the dog because they have not been taught otherwise. There are always exceptions, but for the most part this will be the case. Now is that okay if the dog refuses one retrieve out of 1000, probably.
For me the Force Fetch is more of a transition from 'puppy training' to 'retriever training'. It might very well be the dogs first experience with pressure, and a major bi-product of the effort is teaching the dog how to handle pressure administered from the trainer. It is also, in most cases, a significant 'short cut' in obtaining a known commodity. Now the brutality of the process is subject to debate and will vary greatly between the pro trainer and the guy training his own dog.
For me, HOLD and GIVE can easily be taught to a dog without the use of much pressure. FETCH on the other hand is not something I feel one can achieve MY desired results for without the use of a fair amount of pressure. I want to see gravel spin or cornstalks fly when I give the BACK (aka FETCH) command. I want there to be no doubt that I'm serious. I'm saying THERE is something you need to go get, hold, and return to me in the quickest possible fashion.
Everyones expectations are different, and the amount of time one can dedicate to retriever training is limited for most of us. I just like to move a dog to the end game as quicly as I can. I want them to know what is expected of them and that I am more than willing to enforce any command that I issue.
Just my opinion...