“When in history have people ever had as many children as they can afford? ...”
It depends how you look at it. During times when there were great hardships because of living standards, and access to good healthcare, people had more children to compensate for the mortality rate.
That is different than people having children because they know they can avail themselves of various (Marxist) government social programs, which in many reported cases places their family income far above what it would be if they had to pay for the support themselves. That would seem to be the opposite of “overpopulation (is) humanity hating Marxist nonsense”. This actually encourages larger family size by those receiving transfer payments from people who work, pay taxes, fend for themselves and live within their means. All things being equal, the latter group is not going to grow their family beyond affordable levels.
Large families are particularly noticeable in many low income Hispanic populations, who are more likely to receive support payments in many forms from the government (state and federal). Have you ever heard the term “anchor baby”?