Camlp5 is supported, but was problematic, until I complained on this discussion board - see the camlp5 and 4.08 saga. So, while technically it is still alive and maintained, it is not updated very often. Thus many projects, including Coq, ditched the dependency. Now only a handful of the projects depend on it:
- ELPI (there is an issue to drop Camlp5 support https://github.com/LPCIC/elpi/issues/13 )
- bigbro
- ledit
- orpie - https://github.com/pelzlpj/orpie/issues/18
- logger-p5
- ulex-camlp5 (abandoned and deprecated in favor of sedlex)