I think the implication is that, as opposed to starting a romantic relationship with someone who can support you or a side hustle or etc., having a supportive family is much more passive (and somewhat a roll of the dice, but generally speaking if you were lucky/privileged enough to be born into a family who can emotionally and/or financially support you, there probably isn't much labor/effort you had to put into to make it that way).

It's for sure a huge benefit; I think their point is that it's a huge benefit that doesn't require effort (just chance, or maintenance of good communication/relationship).