Can someone explain the use cases of esc_html?

I’m looking through _s (underscores) starter theme and see that they’re using esc_html for nearly everything. Just an example from functions.php

register_nav_menus( array(
        'primary' => esc_html__( 'Primary', '_s' ),
) );

register_sidebar( array(
        'name'          => esc_html__( 'Sidebar', '_s' ),
        'id'            => 'sidebar-1',
        'description'   => esc_html__( 'Add widgets here.', '_s' ),
        'before_widget' => '<section id="%1$s" class="widget %2$s">',
        'after_widget'  => '</section>',
        'before_title'  => '<h2 class="widget-title">',
        'after_title'   => '</h2>',
) );

My current understanding of esc_html is to use it when we output either data from the database or user input.

Why escape the names of the menu and sidebar?

It’s only available to people that have access to the php files and it doesn’t appear to be put into the db. I looked through the db and couldn’t find anything related to the names, please correct me if I’m wrong.

Is the underscores theme just being overly cautious about everything?

Thanks

esc_html() does two things:

1. Checks for invalid UTF8 in a string.
2. Converts a number of special characters into their HTML entities, specifically deals with: &, <, >, “, and ‘.

Using it instead of __(), _e and other i18n functions protects your website from possible errors that can occur with unaware translators who may use text that contains (1) invalid UTF8 characters or (2) unwanted HTML code. Trust me, many translators will be tempted to use some ‘nice’ HTML tags like <i>, <b> etc, even worse, they won’t close them correctly.