Dick's in his midtwenties, and adventuring solo at this point. If he dies at this point it'll affect Bruce badly, but he can hardly be considered to be responsible for an independant adult's actions.

Jason, eh, kind of responsible, though the kid did wander off on his own to get into the position he ended up in.

Damian, meanwhile, Bruce left in the care of Alfred with the intention that he stick it out while Brucee dealt with the problem. Only for Damian's new sense of heroism to lead him to evade Alfred and get killed while undertaking actions he knew might be deadly (fighting a much larger, stronger and better trained opponent long enough for a civilian to escape).

Even with Steph, her temporary death was a result of her going off on her own to try and do the right thing, only to be killed off (after fighting tooth and nail against Black Mask) by a trusted medical friend of Steph and Bruce's out of SPITE.

TLDR, Bruce getting Dick, Jason and Damian involved with superheroism in the first place (Steph got involved independantly) could be argued to be what resulted in them dying, but that ignores the agency that they exhibited in starting the chain of events that lead to their deaths.

Calling Bruce incompentant because he's busy saving lives elsewhere while his proteges (at least two of whom were told to stay out of it with people there supervising them, in Damian's case Alfred and in Steph's Holly Robinson and her gf, I believe) attempt to do the same thing is kind of harsh.

Even though Jason's is arguably more a result of the kid's own inability to follow simple instructions that lead to his death, rather than a conscious attempt to save lives like Damian or Steph.