BuddyPress.org

In the codex:

https://codex.buddypress.org/how-to-guides/modifying-the-buddypress-admin-bar/

It says:

Any custom code that we create can be placed in a file called bp-custom.php. It gets loaded with all the rest of bp automatically by bp during each page load. If you don’t have one already then create one in /wp-content/plugins/. So we’ll pretend that we have done just that and that our three new functions are going to be loaded with the rest of bp.

but i needed to put the modified buddypress-admin-bar in the functions.php to work.

Is there any reason?