That's pretty damning. Facebook execs knew that extremist groups were using their platform and Facebook's own tooling catalyzed their growth, and yet they did nothing about it.
Facebook have, perhaps accidentally, created a monster of perverse incentives. Not sure what the solution is, besides regulation (which would be extremely difficult).
The solution is only difficult if you start from the basis that Facebook must continue to exist. If they cannot run a profitable business that isn’t harmful, that’s noone’s problem but theirs.