A static class that basically removes all (I think) comment related functionality in WordPress

class-disable-comments.php

<?php




namespace PhilKurth\WP\Tools;




/**
 * Class DisableComments
 *
 * Disables the WordPress comment system.
 */
class DisableComments {




	static function init()
	{
		add_action( 'admin_init', [ __CLASS__, 'remove_comments_post_type_supports' ] );
		add_filter( 'comments_open', [ __CLASS__, 'close_comments' ], 20, 2 );
		add_filter( 'pings_open', [ __CLASS__, 'close_comments' ], 20, 2 );
		add_filter( 'comments_array', [ __CLASS__, 'hide_existing_comments' ], 10, 2 );
		add_action( 'admin_menu', [ __CLASS__, 'remove_menu_page' ] );
		add_action( 'admin_init', [ __CLASS__, 'admin_menu_redirect' ] );
		add_action( 'admin_init', [ __CLASS__, 'remove_dashboard_meta_box' ] );
		add_action( 'init', [ __CLASS__, 'remove_from_admin_bar' ] );
	}




	/**
	 * Disable support for comments and trackbacks in post types
	 */
	static function remove_comments_post_type_supports()
	{
		foreach ( get_post_types_by_support( 'comments' ) as $postType ) {
			remove_post_type_support( $postType, 'comments' );
		}
	}




	/**
	 * Close comments on the front-end
	 * @return bool
	 */
	static function close_comments()
	{
		return false;
	}




	/**
	 * Hide existing comments
	 * @param $comments
	 * @return array
	 */
	static function hide_existing_comments( $comments )
	{
		$comments = array();
		return $comments;
	}




	/**
	 * Remove comments page in menu
	 */
	static function remove_menu_page()
	{
		remove_menu_page( 'edit-comments.php' );
	}




	/**
	 * Redirect any user trying to access comments page
	 */
	static function admin_menu_redirect()
	{
		global $pagenow;
		if ( $pagenow === 'edit-comments.php' ) {
			wp_redirect( admin_url() );
			exit;
		}
	}




	/**
	 * Remove comments metabox from dashboard
	 */
	static function remove_dashboard_meta_box()
	{
		remove_meta_box( 'dashboard_recent_comments', 'dashboard', 'normal' );
	}




	/**
	 * Remove comments links from admin bar
	 */
	static function remove_from_admin_bar()
	{
		if ( is_admin_bar_showing() ) {
			remove_action( 'admin_bar_menu', 'wp_admin_bar_comments_menu', 60 );
		}
	}
	
	
	

}

functions.php

<?php


include 'class-disable-comments.php';


\PhilKurth\WP\Tools\DisableComments::init();