Accountability is a two way street. Staff hold themselves accountable (believe it or not) as detailed above. A Staff Member can't retaliate against your PC without it being logged. In theory, sure, they could load a bunch of NPCs around your PC and insta-gib them. And you could theoretically not file a Staff Complaint, and it would fly under the radar. Just because I haven't seen that to be true doesn't mean it couldn't theoretically happen. Even then, Administrators can (and likely will) run checks on Storytellers, and all of their actions are logged. Just as well, they have to file PK reports (much more required than with Players) and explain what went down. And like Shabago said, they can't create a plot for the sole purpose of killing or even harming PCs. That can be extraneous to the plot, but not the focus of the plot. So as an example, they might have an escaped slave run amok in the Labyrinth and task the AoD with hunting them down. AoD PCs may die in the process, but that isn't the sole intent of the plot.
When I say accountability is a two way street, it goes for players too. Part of the problem with Reddit Gripe #102 is they are quickly disproven when you ask them to post a picture of their request with Staff. It's typically met with resistance, even though they claim they'll never play the game again. More than likely, this is because it doesn't exist. Anonymity can be helpful, and also harmful. I imagine that taking a Complaint request seriously requires time/investigation on Staff's behalf, and creating a way to file requests such as those without any accountability (filed from your account, you're putting your name/veracity/game history behind it) will water down those complaints that are real, and can be verified.
I would say that filing a complaint with the worry you will have reprisal from Staff depends on the nature of the complaint. If the complaint is based in reality, and a Staff member did something to you egregiously wrong, and it can be verified by logs or correspondence -- Why would Staff plan reprisal against you? More specifically, against your PC, because they can't really plan reprisal against you, the player, beyond doing things like docking your karma or banning your account. I've never heard of someone having their karma docked, or the account banned, because they filed a Staff Complaint.
I would also say there is likely a fear of being a stick in the mud with Staff. Filing a complaint theoretically puts you on their radar, makes them more cautious to animate around you, or makes them pull the trigger more forcefully than they might with someone who never filed a complaint before. While I do believe Staff are human beings and make mistakes, I don't think they would be so calculating, cold, and even have enough of a good memory to pull off that sort of action on a consistent enough basis to warrant a fear of it.
I'm very much against anonymously filed Staff Complaints, just as I am against anonymously resolved Staff Requests with Players. The game used to be facilitated through Email, and you could get responses from the 'General Mud Account' without a signature of who responded to your email. It was endlessly frustrating to maintain a correspondence, or to report illicit responses to Staff. The Request Tool (though I dislike it for some reasons, as it takes away focus for IC happenings from the actual game) has created a system of accountability. Any Staff who notes a request has their name put on it. Any Staff who respond or resolve a request have their name put on it. They can't shrug and say "I dunno who did that". Players need to be held to the same standards.