I actually agree with this.
If lightforging were itself brainwashing, then all lightforged PCs would be brainwashed. However, I’d be willing to best that lightforged PCs will continue to always be lightforged but won’t be brainwashed. It follows that lightforging is not in itself brainwashing.
However, you seem to also be entertaining a broader underlying idea: The Light does not use supernatural force to influence people’s minds in general, even through methods besides light forging.
And there I disagree. There’s both theoretical reason to think the Light might influence people’s minds and specific evidence in the history to make it plausible that the Light exercises significant supernatural influence on people’s minds.
On the theoretical end: The Light provides power to its wielders on the basis of the strength of their faith (regardless of whether that faith is factually well-placed, as the numerous fanatical, evil, yet powerful Light users prove). Since the power of the Light for a user is directly proportional to their faith, this provides a feedback loop: Believe more, get more power; more power supports more belief; more belief leads to yet more power. On the other hand, doubt weakens you, so you’re literally punished for questioning your ideology. This provides a natural way to make light-users singlemindedly faithful and unquestioning, since doubt is literally weakness. If a cunning manipulator could set themselves up at the cause believed in, they’d have the most pliable and easy to manipulate army they could want.
Just in terms of in-game examples, there are loads of fanatical antiheroic or villainous light users, from the Scarlet Crusade, to the AU Xe’ra’s forces, to the decadence of Warcraft III era paladins in Lordaeron, etc. The consistency with which we see fanatical devotion to a misguided cause suggests a pattern that fits what I suggested above.
So nah, it’s totally plausible that the Light could become a tool of exploitation and manipulation. And if it is a tool of exploitation, then maybe it’s like that by mistake or on accident – or maybe it’s part of a design.
