You trust people with the right, next generation trust worthy architecture.
When you go for leading edge you often end up with a mix of unproven stuff, assorted approaches, uneven performance and problems nobody ever had. It's fine to experiment, but you should only trust your customers' data to new technology when you find a combination that works well all the time (or, at the very least, when you have mapped all the circumstances it doesn't).
This whole disaster could have been avoided if there were no single point of failure - at the very least, three identical clusters being brought off-line and rebuilt from mirrored data for the upgrade one at a time in order not to disrupt service to users. I am astonished a telco did not know this.