I feel like the issue is partially because fans have known Alastor much longer. They have been kissing his ass for years, so favouritism plays a big part. It can sometimes impede logical thinking or make one forget facts in favour of fanon (been there done that)
And the show purposely plays him up to be this big threat but some people I think, fail to read between the lines that this is like his "mask". He is vulnerable too, doesn't want or like to admit he is vulnerable so he plays on people's fears, keeps them guessing, manipulates them by using /their/ vulnerabilities against them or exploiting them. That way he has leverage. Likes being the one with all the control. Likes being the center of attention.
And it's not that he's not powerful. He is, obviously. But we KNOW there are levels to power in this universe. Alastor is strong but still just a human soul. But the goetia? The Sins? I don't know if he could realistically go toe to toe with them, much less Lucifer? For those who really truly believe that.. I'm convinced they simply forget just /what/ Lucifer is.
Alastor's existence is a blip on his timeline.
You look at Hell and remember that it exists because Lucifer created it. (as far as we know for now)
Whether he meant to or not, he created Hell and everything in it.
It hasn't really been shown yet so I can only make mild assumptions with the little info we DO have, but I'm having a hard time grasping what this man's actual power scale is.
He accidentally willed a whole other afterlife into existence by giving someone a fucking fruit.
