Pinging @jay_villanueva because this is a great feature and workflow that was indeed removed, forgot to report myself. This will allow us to create in areas where network is unstable or non existent (like an airplane, or a place with outages).
From my personal experience, one of my greatest games was created with Project Spark when my ISP took a month to fix my connection, so I was offline for a month (and even though PS needs a connection to publish, it didnt need one to test)