Are there any real advantages in having a third pin?

It seems a minority of razors, usually quality, have that third pin that I guess the shank rests against when the razor is closed.

Does it make the handle stronger or more stable?

I can see how that third pin could relieve pressure on the point-end pin if the razor blade was squeezed into the handle when closed.

Any reasons not to have a third pin, other than cost?

Thats an old barbers tale about quality razors having the third pin. Some of the highest quality razors do not have them including most customs. I think it is just a style thing more than anything else. I guess it could give the blade more stability but I'm really not even sure if it does. I have both and don't see any advantages of one over the other. But that's a personal opinion.