It's a shortcut, but still a huge win. Such shortcuts were possible before, by using state providers, Steemit used that extensively, I used that too, disadvantage was that state files from state providers were not portable so I couldn't share with others, unless they were using exactly same environment. Not to mention that shared_memory.bin these days is less than 20GB, few times less than before the Eclipse.
https://github.com/steemit/steem/blob/master/contrib/fullnode.config.ini#L29
^ Two years ago bumped to 300GB for full node, 15 months ago to 64GB for exchange node.
Bee impressed. :-)