[Rebelgecko]

Boeing still put a capsule in orbit too. And I actually saw those excuses I'm referring to when the BFR prototype blew its lid, which didn't involved even a partially successful mission. Similar things were also said when the Crew Dragon blew up on the ground.

Regardless, testing all of the flight software is certainly not exclusive to SpaceX. I would bet any amount of money that Boeing also tested their software and performed simulated launches, moreover that testing is probably mandated by their contract with NASA. My uninformed guess is that one of two things happened:

1. Their tests were incomplete. e.g. they didn't find some edge case that would cause problems when the T-0 changed.

2. Someone goofed the procedures on the day of launch and didn't update their configuration properly.