The spec deviation for newlines could be done in multiple ways, but the implementations you mention all choose to trigger block constructs (which includes lists

The spec deviation for newlines could be done in multiple ways, but the implementations you mention all choose to trigger block constructs (which includes lists, and also headings) on any start of line. It's because the syntax tweak is intended to avoid confusing people with context-dependent syntax (syntax appears not to work if there wasn't an empty line before), not to give an alternative way to generate <pre>.