And one would think that the other questions raised in the article would not even have to be considered as everyone should know how to swim and vehicles need to be ready to go. This incident has multiple failures by to many people involved.

by leaders led to the July 30, 2020, sinking of the amphibious assault vehicle in one of the deadliest Marine training accidents in decades." (9 Marines were killed.)

After I screwed up. Seems some of these Marines didn't get that lesson.

They're yanking on this chain of command, and others, to find the bad links.

Why weren't all crew trained or certified swimmers, which includes underwater maneuvers?
It seems this battalion commander wasn't in charge of that portion, and was told and assumed they were or would be ready? He had to trust his co-commanders and chain of command.

And the same with the vehicles, someone else was responsible for that, and Regner was trusting them to provide functioning equipment.

And he wasn't told the Navy wasn't launching a safety boat, but someone knew.

Hopefully they'll develop new protocols.
Whenever there's a training accident, they do try to figure out how to make sure it doesn't happen again.

It’s always paid in blood & souls.