"Loss over time" is going to be proportional to the timespans involved. There shouldn't be any appreciable loss at all due to tectonic subduction in a 4,000 year timeframe.
I was arguing from the evolutionary perspective. My point was that even allowing for early fossils to have largely vanished from continental subduction, the vast majority of fossils should be of extinct species. Instead we find that a large proportion, at least 40%, are of living species.
In the orthodox creation model there was rapid plate subduction during the Kataklusmos (look up Catastrophic Plate Tectonics), but that would be largely irrelevant to living/extinct species distributions in a young-earth model. In the YEC model the still large proportion of extinct species in the fossil record would be due to two factors:
1. The fact that many species have in fact gone extinct, compared to the maximum diversity of the original creation.
2. The potential for rapid phenotypic and genetic change among the small post-Flood populations. Natural selection, genetic drift, founders effect, and, increasingly, evidence of directed mutations and expression of repressed genes would have resulted in rapid diversification after the Flood, causing many new species to develop even as original ones died out.
(None of this would require innovative, integrative mutations such as naturalistic evolution requires; these would have been neutral and degenerative trends, such as natural selection weeding out a broad variety of genes for a much more restricted genome.)