Consider, for example, RSS/Atom feeds. Certainly there are <link /> tags you can add, but since none of the major browsers do anything with those anymore, we're left dropping clickable links to the feeds where users can see them. If someone doesn't know about RSS/Atom, what's their reward for clicking on those links? A screenful of robot barf.
These resources in TFA are another example of that. The government or regulatory bodies in question want to provide structured data. They want people to be able to find the structured data. The only real way of doing that right now is a clickable link.
XSLT provides a stopgap solution, at least for XML-formatted data, because it allows you to provide that clickable, discoverable link, without risking dropping unsuspecting folks straight into the soup. In fact, it's even better than that, because the output of the XSLT can include an explainer that educates people on what they can do with the resource.
If browsers still respected the <link /> tag for RSS/Atom feeds, people probably wouldn't be pushing back on this as hard. But what's being overlooked in this conversation is that there is a real discoverability need here, and for a long time XSLT has been the best way to patch over it.
Part of the reason HTML 5/LS was created was to preserve the behaviour of existing sites and malformed markup such as omitting html/head/body tags or closing tags. I bet some of those had the same usage as XSLT on the web.