There's a part of the story where demons are negotiating peace between a town and attacking demon forces. As soon as Frieren hears of this, she says the town is doomed.
Moral of the story is if your problems are caused by a group, don't expect a member of that same group to help you solve that problem.
The anime Frieren has the advantage of being very recent and incredibly popular with normies, but this isn't the first time when anime tackled the subject when the outside forces tried to mingle with the local town. I think the anime Shiki actually had the new folks being friendly and peaceful with the local town.