SitemapXML v.2

[a_berezin]

An XML sitemap helps the search engines to find all your content

Sitemap does not help if you have a site with a poor structure, no unique content, without reviews, inconvenient for visitors.
If you have a good site, all the necessary pages are found and indexed without a sitemap.

helps the search engines report back to you how much of your site is indexed

Yes, I agree, as a tool, site really allows us to determine how well your site is indexed. And wonder why some of the pages are not indexed.

ease of use (especially for search engine spiders)

Do not think about the comfort for robots, think about the convenience of visitors, but do not forget about the robots. Do not forget that sites appreciate not only the robots, but the assessors.