The enable_collect_history setting

When the setting is true, you can specify the COLLECT HISTORY clause on users, groups, and databases. The system enforces those settings when users connect to the system.

Suppose that you created a history configuration with some users and some databases to have COLLECT HISTORY OFF.

When the setting is true, the collect history setting is enforced and history is not collected for those users and databases.
When the setting is false, the system no longer enforces those settings, so history is collected for all users on all databases.