Currently, Zabbix does not support High Availability (HA) operations out of the box. Zabbix is known to work in HA mode with the help of third-party HA clustering solutions (such as Pacemaker) but the barrier to entry (high learning curve for HA software, complicated network settings, error-prone cluster configuration) can be too high for small to medium Zabbix installations.
Zabbix should offer a simple but reliable native solution that would make HA installation easy to set up and operate.
It's understood that the simplicity aspect of the native Zabbix HA solution has its trade-offs and may not cover all HA requirements, especially for very big and complex installations. Thus, the native solution should be opt-in and not interfere with the third-party clustering software, should the user decide to go their own HA route.