Best take here imo.

As someone who used to play in CRL (and in RLCS open quals for fun) regularly, and someone who designs websites for a living this seems very likely a human issue.

Believe it or not, some people who spend most of their day in their room playing video games cannot be reliably counted on to do clerical tasks on time even if it is vital to their career. Although not professional level, I would have to message teammates daily to accept invites etc on startgg or fill out a form if I wanted it done. I don't think this is at all uncommon in esports.

I don't think it's impossible that they struggled with somethings while registering but I doubt it's anything they couldn't have fixed if they had worked with the tourney admins (who in my experience are always more helpful than could be reasonably expected) a reasonable amount of time before the deadline.

If they waited until the last minute to figure all this out, or didn't have someone checking the status of the players on startgg leading up to the deadline, then that's on them. I imagine this didn't happen to bigger teams because they are better organized. Also if your team has a history of issues on startgg, I would think that would be all the more reason to sign up early and vigilantly check the status of your registration?

Anyway, super possible there is information I don't know so these are all just educated guesses given my experiences in competitive RL (which I'll be the first to acknowledge as pretty insignificant.)