Runtime control of logging level per process type or per process is the best troubleshooting and debugging feature ever. Unfortunately, as more and more debug logging is added to various places of Zabbix it's usefulness diminishes as it is getting harder and harder to find the needle in a haystack. Log files grow and rotate too quickly, messages of different processes get too interlaced and so on...
For example, TLS code produces lots of debug, which is good for troubleshooting encryption, but if TLS is fine and I'm only interested in "trapper got '...'" messages it just makes my life more difficult.
Idea is to have more granular control of logging level.