Let’s not blame any one group for a bigger issue. In my experience, there are many amazing shadchanim who work very hard, including rabbonim, rabbeim, teachers and rebbetsins. Friends and neighbors also play an important role. I’m sure there are yechidim, whether shadchanim, parents or individuals who make mistakes. But by and larger this isn’t the case.
The fact is that is that it often becomes harder to make a match as the prospects age out of the primary dating age. The best solution is to do what you can to help. As a friend, as a neighbor, or even someone who lost touch. Daven for them. Have them over and support them emotionally in life, not just in shidduchim. Do what you can, do your personal hishtadlus, and then daven and be a good friend.