Others have already talked about the potential benefits of matchmaking, but not a lot of people have talked about marriage as a joining of families. There are lots of cultures where it’s normative to live together with parents and grandparents (which if you think about it also means aunts and uncles, cousins, etc.). There are lots of benefits to people who live this way - greater financial stability, access to childcare, healthcare, increased lifespan, lower depression - and so it makes sense. If you are bringing someone new into the household, it may be important for the heads of the household to weigh on or even choose the person or the family.