This is an opinionated curated documentation of previous RFC discussions that failed to result in a successful change in PHP.
The purpose of this information is to provide to people a summary of why certain ideas failed to get done, so that future conversations can be far more productive, and avoid people continually asking "why did this feature never get done?".
The curation is opinionated. I'm not going to document some of the discussions that were had that were either for things that were a bad idea, or just so unlikely to happen that curating them isn't likely to be worth anyone's time reading them.
For reasons, the actual list is here: RFC Codex