The algorithms are all a black box, but What Is A URL And Why Do They Matter For SEO? - Moz says
While using a URL that includes keywords can improve your site’s search visibility, URLs themselves generally do not have a major impact on a page’s ability to rank. So, while it’s worth thinking about, don’t create otherwise unuseful URLs simply to include a keyword in them.
We already send a few strong signals for categories in addition to what’s on the page (and based on the site hierarchy, Google also knows that this support topic is linked to from the meta.discourse.org/c/support).
Like @Falco said, we added the category to page titles, but we do also have appropriate schema.org markup that contains categories in the breadcrumb.
All these signals are strong enough that Google includes the category breadcrumb in search results instead of the full URL:
Considering Google already knows that the example link above is within the howto page hierarchy, I would be surprised if the category in the URL would make any difference.