Why is Apache owned by "nobody"?

The "nobody" user is a special user that generally possesses the minimum amount of permissions/access to complete a particular task.

From a security standpoint, this would prove beneficial as it wouldn't have access to tamper with files you wouldn't want it to access. This, in turn, limits access to site content files that are viewed publicly. As a result, select services such as Apache make use of this user. Processes spawned by Apache are under the "nobody" user, and the "httpd" processes owned by the "nobody" user would typically represent an active client connection:

[root@server ~]$ ps -u nobody

  PID TTY TIME CMD

26057 ? 00:00:00 httpd

26058 ? 00:00:00 httpd

26059 ? 00:00:00 httpd

26060 ? 00:00:00 httpd

26061 ? 00:00:00 httpd

26441 ? 00:00:00 httpd

27931 ? 00:00:00 httpd

If you're experiencing a high count of these processes to the extent it began impacting performance, then you may want to look into reducing the MaxRequestWorkers value.

For more information on MaxRequestWorkers and instructions on tuning it, you may review the below article:

https://support.cpanel.net/hc/en-us/articles/360047992273