Indexing decay is a real issue. Google is becoming more restrictive on what pages should be indexed; both in terms of content, technical aspects (performance, structure), site aspects. It's more important than ever to have software that helps you identify and monitor issues, alerts you to indexing statuses, and gives you a way to seamlessly send these pages back to be indexed. Remember: Both traditional SEO and newly minted AIO (or GEO, AEO) requires your pages to be indexed to show in results!