Stacked PRs is mostly a way to avoid thousand- or tens-of-thousands- LOC branches, which makes each PR meaningfully reviewable. You need a good code review process for it to become useful. It’s very pleasant once you are accustomed to it.

I’ve seen successful teams that regularly do reviews of massive PRs and feel this serves them well enough. I suspect it just places a lot more trust on the developers to get the details right so reviewers only look at larger design issues.

The language of choice is not relevant. Even before AI, one can accumulate thousands of lines of c++ easily.