TL;DR -- I think it's super weird that defilers aren't alignment locked while classes that work similar forces are.
I don't think this is going to win me any friends, because I think by and large the community resents alignment restrictions on classes. There's an argument to be made that despite alignments being cosmic forces of good, evil, law, and chaos, that we as players, and possibly even the DMs apply these concepts arbitrarily, situationally, and subjectively. And while I'm not ready to open another alignment debate, I'm sure this'll spark one. Hence, the nature of the unfun question:
Why is Defiler not Neutral and Evil locked? Hear me out about this; Palemasters are evil. They require an -award- to be played as -not- evil. The reason for this is that they do vile things to themselves with negative energy, and their main mode of dealing with problems, as presented by the class is -evil- in nature. Not just from a subjective point of view, but from the very cosmic laws of reality that have been established within the Forgotten Realms setting. It is evil. It is -very- difficult to be a goodly palemaster, because even with pure intents, you, by the nature of what you are, spread and propagate evil.
Hemomancers are alignment-locked to non-good as well, for much the same reason. Their magic is mostly dark and sinister, and no matter how perfectly wholesome their intents may be, by the nature of what they do, they -spread evil and entropy-.
Hexblades are just sick as hell. I have nothing to say about them they're cool AF, please keep them evil locked so people don't ruin the aesthetic.
Anyways, to get back to my point. The main gimmick that defiler clerics revolves around is pumping so much negative energy into a thing that it -dies-. If this isn't on the same level of disruption as hemomancy, animation, or palemastery, what -exactly- separates defiler-pathed clerics from these classes? What makes a defiler more worthy and good?
And therein lies the other part of this. If it can be argued that defilers should be allowed to be good, why not palemasters? Why not hemomancers? Why not hexblades?
I'm asking for a conversation on setting consistency here. Because I firmly believe that no matter how pure a defiler's intentions are, if they work overwhelmingly in negative and entropic energy, it should leave a stain on their soul that prevents them from having the good alignment. Thank you for coming to my ted talk.
Edit:
Just to drive my point home, here's the defiler path token description in game: