wp_reset_query() - ensure that the main query has been reset to the original main query
wp_reset_postdata() - ensures that the global $post has been restored to the current post in the main query.
https://wordpress.stackexchange.com/a/144344/14380
If global $wp_query is being overwritten, wp_reset_query() resets this back to the correct global $wp_query
If those widgets used a different variable for the query, like $loop = new WP_Query(), then we could use wp_reset_postdata() as the only global variable that needs resetting is $post.
https://github.com/copyblogger/genesis/issues/1693