They're really only doing that for hipster cred. That way they can easily write articles titled "How I made (really simple/trivial application) with (really fledgling technology)" such as "how I made a twitter client with node.js" or "how I put 2 sprites on the screen with webgl" or "how I managed 2tps with java".

We know all financial companies use databases running on tandem or tuxedo. But that's not cool sounding. How are they supposed to get fun jobs doing nothing with catered lunches? HOW, HOW I ASK!