Google's John Mueller posted on Reddit that he agrees, that HTML sitemaps are not worthwhile for SEO purposes. He said "I agree. When it comes to SEO ... for small sites, your site should be crawlable anyway (and if you're using a common CMS, it'll almost always be fine) & for large sites, they're not going to be useful anyway (use sitemaps, use normal cross-linking, check with a crawler of your choice)."
For users, that is another thing he said. He wrote "Do they make sense for users? I guess it's a good signal that your normal navigation & in-site search are bad if people end up going to your HTML sitemap pages :)."
Old school SEOs forever have said HTML sitemaps is an important part for SEO.
But the truth is, if Google cannot crawl your small web site through your normal navigation, then you got bigger issues. And most sites provide XML sitemaps for search engines. But as you can see from John above, large or small sites, it seems HTML sitemaps don't really give you a value add for SEO or ranking purposes.
In 2016, John did downplay the importance of HTML sitemaps but in 2009 Matt Cutts said HTML sitemaps come first. Times have changed?
Forum discussion at Reddit.