Because comparing the same thing done the 'new' way and the 'old' way is one of the best ways to see the differences between the two ways and find out if and when the new way is better.
Because doing ${things that exists} in ${current trendy programming language} is somehow gauged as a Good Thing™ in your portfolio by the startup mindset.
Because posting this Good Thing™ on Hacker News is basically the SF startup scene's own LinkedIn equivalent.
Because other people who has bee doing this Good Thing™ want their own Good Things™ to be validated as well, so they continue this tradition.
Because Conservatives are always on the wrong side of history. And new things replace the old, and there is a reason C is the biggest language of them all.
I don't have a problem with people scratching an itch. This is how we practice our craft.
However, how is writing yet another NES emulator anything but conservative given the vast number of example and documentation to draw from? Sure, it's not as simple as writing yet another TODO list in yet another JavaScript framework, but it's not 'new'.