Do box office bombs derail acting and directing careers?
This raises some questions as to interpretation. I think it makes more sense to talk about this as regression to the mean and an 'audition' view of things. The flop doesn't 'destroy' their career, it merely means they failed the audition for a higher role.
You highlight as paradigmatic Cimino and Stanton as having 'fallen' after their flop, but if you remove your selective citation of _Deer Hunter_ and _Finding Nemo_, their careers don't look *that* different before/after. Cimino had made one low-budget film 4-5 years before _Deer Hunter_, and he... went on to make more low-budget films at a roughly 5-year cadence; he just didn't get to make another ultra-high budget AAA film like _Heaven's Gate_. Stanton was disgraced by _John Carter_ and didn't direct another huge live-action extravaganza... but looking at his filmography https://en.wikipedia.org/wiki/Andrew_Stanton#Feature_films _Finding Nemo_ had been his *only* director spot, and he continued working high-profile films (writing/producing), directing episodes, and a bunch of other stuff, he just didn't get to direct Pixar's main films _Coco_/_Soul_ etc. Interpreting the subsequent smaller projects as 'killing their career' seems a bit like asking why the lottery winner got so unlucky when he bought another ticket & it didn't win.
They hardly got turfed out of the industry; considering how many people are avid to, and never get to, do as much as Stanton or Cimino got to do after they supposedly were exiled to Siberia for their flop, it doesn't seem like there was much 'effect' on their baseline career. It looks more like they were given an opportunity to 'take it to the next level' and when it 'flopped', they were presumed to not have what it took for the next level & to be the next Steven Spielberg - but to remain highly competent & hireable at their prior level.
Similarly, the actors: it doesn't sound like they were penalized so much as remained on their original trajectory. If that trajectory was misleadingly high, because you've cherrypicked actors coming off huge one-off anomalous successes, well then, they are going to regress to their lower mean as they 'fail to show the right stuff' with a standout performance. And if they are a well-known quantity, then a flop offers little information on their talents, so no one cares or punishes them for it. (I mean, what, if Eddie Murphy is in a flop, are you really going to conclude, 'oh, I guess the man was never funny after all'?)