I believe that the person who needs to benefit the most is the client. Sometimes, there are referrals to other professionals without the reciprocity that you seem to be looking for.
When I know of somebody who can help my client, be it a dietitian, chiropractor, massage therapist or else, I will refer my client without expecting a referral in return. Often, a partnership will develop based on mutual professional respect, and that may include referrals.
I found the old adage “What goes around, comes around” to be true. I sometimes get referrals from people I don’t even know personally but when I dig around, I usually find connections made previously to somebody else.