"But what if they could afford them at the time but something changed for them."
Why is it that whenever a general problem is discussed, specific "exceptions to the rule" are trotted out?
The vast majority of people across the world (including many in the UK) who breed to excess cannot, by their own efforts, afford to support their brood properly. Many of them are unable, from the outset, to afford to feed and clothe their children adequately without either charitable support or State aid. It is a ludicrous situation where nations such as the UK are clearly over-populated (with all the associated problems that brings) and the government is struggling to provide essential services whilst paying people to breed. It's the economics of the madhouse.
People who were self-sufficient but hit hard times through accident, tragedy or misfortune can be assisted. Those who churn out a child every 12 to 24 months secure in the knowledge that the State will pick up the bill for their ever-increasing brood should realise that in the real world bearing another child brings extra costs, extra responsibilities and a considerable extra threat to the planet.