Whitespace is cleaned up around the split point, as in the large majority of cases it would cause issues to have extra lines at the top or bottom of any chunk of text.
It is problematic in most word processing style contexts, where paragraphs are separated with a single newline, but specific to Scrivener, one could inadvertently create visible section breaks with some compile formats. If you poke around through the back-links in that thread, you may find a sprawling network of confusion stemming from people treating whitespace as casual aesthetic padding and ending up with it being treated semantically—as a break between minor sections.
So overall we do our best to keep whitespace from accidentally ending up around document edges, and anything deliberately doing so would be conceptually very messy.