The logician would argue, You only live once should be rewritten as You live only once, with only next to the thing it qualifies, once.
The logician would be unbearably pedantic, but there is a grain of good taste in the pedantry. Writing is often clearer and more elegant when a writer pushes an only or a not next to the thing that it quantifies. In 1962 John F. Kennedy declared, “We choose to go to the moon not because it is easy but because it is hard.” That sounds a lot classier than “We don’t choose to go to the moon because it is easy but because it is hard."
What has emerged here is that although survivorship bias probably does contribute to that to some extent, it is not the main explanation: premodern buildings may on average have been a bit less beautiful than those that have survived, but they still seem to have been ugly far less often than recent buildings are.
The survivorship theory sought to explain the apparent rise of ugliness in terms of a bias in the sample of buildings we are observing. There is another kind of bias theory, which seeks to explain it in terms of a bias in the observer, saying for instance that every generation is disposed to find recent buildings uglier than older ones, and that this is why recent buildings seem so to us. This is a complex and interesting idea, which I am not going to assess on this occasion. Suppose, though, that our eyes are to be trusted. If this is so, strange and eerie truths rise before us: that ugly buildings were once rare, that the ‘uglification of the world’ is real and that it is happening all around us.