Family assistance is more than just cash though. If my mother helps me look after the kids twice a week for free, that frees up hours I could use to "get ahead" in life (study, prep for interviews). Should that not be allowed?
Yes. But even so, that doesn't make it immoral to help your children of for children to accept that help.
Being in favor of a better world tomorrow doesn't mean that you can't play by the rules of the world today.
Every election, I vote for policies that will considerably increase my taxes, but at the same time, I expect my CPA to make sure that I only pay the taxes that I'm legally required to pay.
If make it less so means reducing personal freedom to the point of regulating how much time a grandmother can take care of it's grandchildren, I really strongly disagree with that vision.
I believe the solution is probably more along the lines of taxing everyone fairly, and using some of the funds to provide free or affordable childcare to everyone who wants/needs it. Likewise with other forms of family support/advantages. Provide alternatives for people who don't have things by birth-lottery.
So you can still have grandma watch your kid all you like, while the person who has no living relatives can still have a kid and hold a job by taking advantage of subsidized daycare.
One of the things I realized watching the tv show Revolution was that every time someone had a choice between "my child might suffer, even a little" and "destroying the whole world" the parents on the show chose the destruction of the world every time.
Parents routinely choose selfish outcomes at the detriment to their children and society.
Not vaccinating your children not only affects your immediately family, but everyone's children around you. That is the most obvious example, others include indoctrinating children in religion is another.