Because normally no-one stops them. They approve the drug, side effects be damned, then in a couple of years they quit their job and get hired into the C-suite of whatever pharma company they approved the drug for, while another exec from a big pharma company fills their role as "regulator", round and round they fucking go. It's a big club and they'll hit you over the fucking head with it. A criminal referral is a start, but nowhere near the end. That will then rely on the prosecutor being motivated to actually try the case and lucking out on a judge that isn't an ideological nutjob who will dismiss the case for whatever made up reason they want, probably something like "standing" or some vague bullshit. I wouldn't be surprised if some jewy outfit tries to sue to prevent these fuckers from being indicted at all.