This is evidently untrue. The principles of architectural schools and trends can be objectively evaluated. We also have some historical evidence of lost buildin

This is evidently untrue. The principles of architectural schools and trends can be objectively evaluated. We also have some historical evidence of lost buildings that show they were not all the ugly ones. And we have many buildings that were not preserved intentionally that are nonetheless beautiful. Perhaps you meant that inferior or cheaper schools of architecture co-existed with the prestigious architecture of their time. That is less controversial (and is also true today, mercifully.)