Every rule has its exceptions. Sometimes it's nice to be able to quickly verify that the person answering a very specific comment about a specific company works at that company by avoiding the initial confusion or having to click anything. Let's not be overscrupulous.
Applies to job title, too. Yes, even at companies who are special enough to get millions of dollars from VCs.
source: "In Comments" https://news.ycombinator.com/newsguidelines.html