What happend to these supposed protector people, that was stated before to protect this city or am I just misinterpreting what was stated previously. I know that the higher up people will protect the city after the draconic realm which was promised. Whatever, I am not supposed to think when I read stuff I guess...
@tyson288 if put bluntly, it's not within the scope. i could be wrong but the long answer:
i think it's because they already formed soul seal with different teachers for different sects, as we know nether and the other teachers are in amiable relationship cause they're all from tiny world. then possibly cause the demon lord's actually from glory city which makes it an internal problem, whereas the nether lord's protection is from external stuff(eg. demon beast hordes, the guy that demanded yuyan be handed over n fought nether lord, etc). might b why nether probably wont interfere in the fight between students here(demon lord aim to take something and maybe rule over instead of wiping glory city out of existence also a factor).
from hints of nether and the others' conversation, we can also assume their sects in draconic realm are under pressure from the sect where the guy demanding yuyan is from.. there r other matters to prioritize on than their disciple's scuffle, unless it gets really out of control then they probably wont directly interfere
like nie li's hunch, demon lord's close to getting into next stage of cultivation (forming the first fate soul). they're not strong enough to kill demon lord, so demon lord win and someone will die.. which is more fuel for nie li and the gang to wana get even stronger
Nie Li's father in law dies by self-destructing completely shattering his soul with no point of resurrection (so far in LN) -> This loss renewed Nie Li's determination to gain enough strength to protect everyone that is important to him - classic trope