The option to have no separator at all has been asked about before. In most cases it wouldn’t be terribly useful and would result in the last paragraph of one section merging with the first paragraph of the next. There are certainly some edge cases (e.g. you could have a sequence of binder items that are one-liners and have them merged into a paragraph) where it could be seen as useful, but not broadly enough to add what would for most cases be a confusing option.
That aside, I don’t see how a setting like that would help since it would no longer be inserting a page break. Even so, that isn’t something Scrivener is doing, it’s a bug in the Qt exporter that is too deep for us to get at easily.