> kiss goodbye to any notion of being able comprehend existing code that's not written by you (until llms arrived).

In my experience it takes a while (<=3 months) for folks to become proficient when they see an alien dialect of c++. That may sound totally unacceptable to you (fair). Cpp is also a “big tent” language in that it is genuinely multi-paradigm.

I think LLM’s might help, but sometime they hurt too (confidently/persuasively wrong analyses). The gain is large for small/trivial contributions. For changes that require genuine understanding, I’m not sure (large error bars personally as to whether the sign is even positive).