I agree that people should make shidduchim because it is a mitzva and not for the money. However, I am someone who most probably could not be a shadchan, although I would love to be one. I don’t want to be a shadchan for the money, which is why I have called mothers and friends with suggestions and told them if they were interested to go find a shadchan and I have also made suggestions to shadchanim and told them they should take charge if they thought it made sense.
Being a shadchan is a service. If one wants to use that service, there is a fee. If you don’t want to use the service, there are other ways. The child can scout out eligible partners by him/herself or a friend or relative can set them up. If someone wants to use a shadchan, it comes with a price.