[bzbarsky]

That's a bug in ycombinator's linkification code. A quite frustrating one, since <> is _the_ standard way to delimit URLs in plaintext (going back to earlier than section 2.2 of RFC 1738, back in 1994!), so having linkifiers that still fail to respect it is really unfortunate.

[wilg]

Is there a reason to delimit a URL in plaintext? I can't recall ever seeing this syntax before and I don't really see a need for it.

[bzbarsky]

Yes, there is. Consider a URL followed by punctuation. How do you tell whether that comma, period, question mark, etc should be included in the URL or not? Had I put in a link to https://www.ietf.org/rfc/rfc1738.txt in my original comment instead of "RFC 1738", there would have been a comma right after the URL, for example.

The possible solutions to this punctuation-following-URL problem are that you delimit the URL, contort your sentence so the URL is followed by a space and some other words instead of punctuation, start adding random whitespace after the URL but before the punctuation to avoid the linkifier eating the punctuation, or stop putting URLs in plaintext. I've seen all of these used; the first solution is by far the best.

Oh, and that's all from a Western perspective. If, on the other hand, you're using a language that does not use space-separated words (e.g. a number of East Asian languages), then delimiting becomes even more important, because you can't just guess that the URL ends at the space character; there are no space characters around.

I can't speak to your experience seeing or not seeing this syntax, but as I said it's been part of the URL RFCs for over two decades, is used in other RFCs where URLs can appear (e.g. the Link header syntax), and is reasonably commonly used by people who both put URLs in their email and want to punctuate it properly. I will grant that proper punctuation is out of fashion in certain demographic groups. As is writing plaintext, I guess.