There are many shadchanim that have been extremely successful, and we can not take that away. but many of these shidduchim that were made were not thought of by that shadchan, someone suggested it to them, and the shadchan took it further.
Once they become famous for making so many shidduchim, it is easier for them to get yesses from the boy or girls parents because they have that name already and are considered such a successful shadchan.