Reported by a user through the CTRL+ENTER functionality in documentation:

Page: Appendixes > Process configuration > Zabbix agent 2 (UNIX):

Request: Please clarify that having an empty "Server=" setting is allowed, and it can be used to prevent Zabbix Agent 2 from listening on port 10050 at all, to only use active item. (With Zabbix Agent you can use "StartAgents=0" but it does not work with Agent 2).

Documentation and Zabbix agent 2 configuration file update should be considered.