This is ambiguous about cities or nations that resisted and then surrendered. There seem to be a lot of references to how surrender was followed by everyone being killed or enslaved. I kind of think that's an area of contrast between their standards and today's. You can point to "civilized" countries destroying whole cities in the 20th century, but doing it after your enemy is defeated is much more frowned on.
Also, when you say "beneficial for those who followed him" it elides what it meant when they enslaved the women and children from a conquered population. I don't think they generally allowed individuals to choose whether to be among those massacred or not. And what happened next probably wasn't consistent with modern human rights standards, which again, I think goes back to the original point that started the subthread.
This is an extremely odd thing to say about authoritarians right now, although this may be my American perspective, since people have been pointing out recently how futile it can be when dealing with police in the US. Still, I kind of think it's universal - being polite to authority is utterly useless once you are a suspect, thought to be dangerous, or have something they want.
It made a lasting impression on me when I was stopped in my car as a teenager and an officer decided that I must be a drug smuggler because I was too quiet/nervous.
Edit: I guess if you interpret "everything" broadly enough, your statement is somewhat plausible, but "everything" includes many situations where an authority asks you something that is theoretically or ought to be voluntary and you have to be aware that it's not really a choice. And it's still not always true.