In the recent Obsidian PAX panel, they specifically mentioned putting in the option to start a fight against an enemy who was just too powerful to beat (I'm guessing one of the Archons), which had QA ask them why they put the option in. After that, they decided to remove the option or at least made taking the option not result into death.
Watch again, they didn't say it was removed. They added a warning and an option to back off.