There is a reason for that and it's because the mods take a hard line on editorializing the title of the submission. It's likely done automatically by a bot though.
from the guidelines[0]: Please don't do things to make titles stand out, like using uppercase or exclamation points, or adding a parenthetical remark saying how great an article is. It's implicit in submitting something that you think it's important. ... Otherwise please use the original title, unless it is misleading or linkbait.
Indeed. In this case it is misleading simply to call it by the title "The Matasano Crypto Challenges". Specifically, this is a blog post about the Matasano Crypto Challenges.
The modification wasn't intended to make the title stand out, and it wasn't editorializing, it was deliberately adding information to help you, the reader, know what it was you were clicking through to.
I understand the reasons, but I feel that sometimes the mods revert titles without thinking, and without assessing why it might have been changed. Again, I understand the reasons, and having yet another time sink is perhaps unwelcome, but I'd like to see some way - like the "vouch" mechanism - where altered titles can be accepted.
0. https://news.ycombinator.com/newsguidelines.html