Raubahn EX wasn't simply due to players logging into the game but rather how the MSQ immediately forced everyone into an instance within five quests. This made it so players didn't naturally funnel off into a variety of activities you'd expect with a new expansion but were all bottled necked at the exact same point, all trying to queue into the same instanced at once. The same issue occurred at the beginning of Deltascape because Yoshida gave into the dev team begging him to allow them this "super cool" instance. With predictable results.

Hence why come Shadowbringers, we didn't have any instanced content until well into the MSQ and the branching path for Allise and Alphinaud were made considerably longer. They also launched the expansion with every single new city having extra instances to split players up. In other words, they learned a harsh lesson from SB and aren't likely to repeat it.