It was obviously an exaggeration to say there are NO tall buildings in Barcelona or Paris. There are some and they are mostly all office towers not residential buildings. But most of residential Barcelona and Paris look like this rather than Manhattan.


And the fact that they are actual cities rather than mile upon mile of single family housing doesn't turn them into 3rd world slums. To the contrary. People from around the planet flock to both cities because they have lively safe streets for pedestrians. That is part of their appeal. Accommodating more people doesn't mean you become either Manhattan or Cairo.
None of this contradicts my main point which is that if we want to build a society that encourages marriage and families by making it possible to afford housing, especially on one income, then we need to be much more creative about how we build housing in this country and not turn out cities into nothing but playgrounds for the very rich and very poor. There are reasons why young families are fleeing big cities and it is mostly to do with affordability and availability of housing. Not exclusively, but that is the biggest driver.
Of course this is a much bigger issue in places like California and other big cities and fast growing parts of the country than it is in say rural West Virginia where there are other issues such as jobs and the economy rather than housing that is holding people back. It is also a bigger problem in liberal cities and states than conservative ones for a whole lot of reasons both good and bad.
Also, accommodating higher densities in the centers of our big cities so more families can find homes isn't going to change suburbia or rural America in the slightest. Allowing higher density in San Francisco, Los Angeles, or Seattle isn't going to affect Josh in his rural Ohio double wide in the slightest (I seem to recall that is what he said he owned). If anything it will result in less people spilling over to rural areas. So I'm not sure why the resistance.
But if we want to encourage marriage and families there is a whole lot more we can do in a whole lot of areas starting with housing.