It was the standard way to format URLs on Usenet. GP is at least 40 years old.

Carry-over from Markdown, and it appears to help HN's URL parser in some instances:

<https://news.ycombinator.com/item?id=32745065>

RFC 3986, from 2005: “Uniform Resource Identifier (URI): Generic Syntax”:

    Using <> angle brackets around each URI is especially recommended as
    a delimiting style for a reference that contains embedded whitespace.

<https://datatracker.ietf.org/doc/html/rfc3986>

In markdown (or at least some flavors) that is the typical way of making a hyperlink actually a link. It's equivalent to [link](link) in markdown.