Ah, but society prefers[1] if people choose to take that responsibility and raise kids. I haven't seen evidence that society cares about whether one goes hiking for 3 months or not.

Now, you may be right and in the minority that this preference is wrong, and we should allow leaves of all kinds. But you will have to convince people to vote for legislators who will mandate those sort of policies.

[1] Evidence that society wants people to raise kids: child tax credits, FMLA policies, demand from the leading presidential candidate for increased parental leave etc