FutureSDguy, the buyer can even inform the listing agent that he/she will represent themself. Also as you said they can ask the listing agent to represent them for any commission they want. After all, all commissions are negotiable. It is doubtful that the listing agents broker will allow it but the buyer can certainly ask.
It is simply the quality of the representation that is in question here. Most everyone here feels that realtors are not worth much if anything at all. That is okay and certainly understandable. Most all transactions work out okay for people. However if you are the unlucky person who happens to have taken the shortcut and you get boned, it can be a very expensive lesson.
Lets say you had the listing agent represent you in a purchase… lets say the home have polybutalene plumbing and the other comparable home down the street didn’t have poly but in every way was just as comparable. Would that listing agent encourage you to consider the other home?
I think that when you buy a home you really want to enlist as many advocates as you can. A good realtor will not press you into buying a home just to get the commission. If the realtor is good, they know you will buy eventually, whether it is a week later, or a few years later. Again, many people do not see value in the representation and experience a good realtor can give you. Those that do, certainly benefit. If you ask enough of your friends, you will eventually come across someone who did find great value in a realtor. It may take awhile but you will.