I think Gale's written to be mostly at fault of his own downfall. The other companions are not. Astarion maybe would have been, if his past hadn't been cut. Whether Gale's folly being his own fault is "right" or not is a different matter, but I'm pretty sure Larian intended it to be this way.
We all know by now that they're not very good at being consistent with their own narrative and themes.
Oh for sure. I don't think anyone who discusses Gale's history means to diminish his accountability. He made his own choices. But in a way so is everyone else (aside from Shadowheart and Lae'zel who were children).
Astarion's previous acts as a magistrate got him killed by the Gur, which led to him becoming a vampire spawn under Cazador.
Wyll chose to make his pact to save the city.
Karlach chose to work for Gortash (and he ended up betraying her).
Gale chose to go for the orb.
But it's the proportionality of the consequences of their actions that lend toward an abuse narrative. Astarion was a terrible magistrate, that doesn't mean he deserved to be Cazador's thrall. Wyll even admits he doesn't regret making his pact, but that doesn't mean he deserves Mizora's abusive treatment. Karlach errored in judgment when she chose to work for a man like Enver Gortash--that doesn't mean it was also her fault when he betrayed her.
Likewise, with Gale, he made a horrible mistake when he overstepped Mystra's rules and went for the orb, but that doesn't mean he deserved to suffer from the debilitating and lethal consequences of it--or be told to blow up.
Many of them are victims of their own decisions, their own weaknesses and flaws, but also victims of greater forces beyond their control.
