There was a period where Hacker News consisted primarily of people on the right-hand side of the spectrum. People who were working inside of startups or had lots of experience with the web and our industry. Pretty much everyone knew what sharding was, and MongoDB wan't very popular.
These days we've got a lot more people and they show up all across the board.
Clearly if this is on the homepage, it was voted there by your peers. This kind of knowledge is completely obvious to many of us, but not everyone is on your level. Cut 'em some slack.
