As was the case with planned theme and plugin auto-update functionality, the WP hype machine is full speed ahead touting the revolutionary planned Native Support for XML Sitemaps in WP 5.5 ! Examples: here, and here, and here.
And … *yawn*.

First, does an XML sitemap provide any tangible benefit? Probably not. It was a different story back in 2005 when google introduced sitemaps. At the time, and for some time afterward, sitemaps were beneficial on websites where:
- The site used non-HTML content like Silverlight or Flash; or
- The site was large and there was a chance for the web crawlers to overlook some content; or
- The webmaster was not very good and making sure all content was logically linked together.
But in the years since 2005 the popularity of non-HTML content has waned, the capability of search engine crawlers has steadily increased, and tools such as WP have made logically linked content much easier to achieve. In 2020, a sitemap is unlikely to provide any tangible benefit.
Should my site have an XML sitemap? Sure, why not. It’s easy to do using Yoast or another popular SEO plugin, it does no harm, and who knows – it might provide a bit of SEO boost in some one-off situations. But if I don’t have a sitemap I’m not gonna sweat it.
So, why is WP adding this capability to core? IMHO it is a good incremental enhancement. Lots of purported experts still recommend sitemaps – some even tout sitemaps as essential. As a result, lots of WP users want sitemaps. The good people at WP are making this high-demand, almost-useless functionality easier, without the need for a plugin. Good for WP – I’m all in favor of this.
But why the hype? I dunno.

