Possibly.
I've had to do death notifications, go over medical examiner reports, and even had to see a few people die up close & read what was announced about the situation later.
Freak medical situations, drug overdose, undisclosed ailment/disease the family doesn't want public, and sometimes people's bodies just decide it's time to check out.
Overall, an obituary is a legally required step. And, it can be painful for those left behind to share the reason.
It could also be fear of some sort of stigma attached to the cause that makes them keep it to a minimum. (Drugs, AIDS, suicide, etc).