They maintained the site. Kept it operational. Improved it occasionally. Made sure it was up. They made some money from advertising, helped cover their expenses and then some. They actually made a profit.
Profit was a motivating factor for The Pirate Bay to provide a relatively reliable service!
What is the purpose of 372 or 5,570,549 unmaintained garbage mirrors of a possibly dead site?
Having a mirror requires almost no skill and there is no motivation to maintain it, improve it and no financial incentive as "Open Bay" is "Open Source".
Is this an achievement? The news article is from VentureBeat.com, and I bet those venture capitalists are just swarming to get a piece of the action? Err. No.
And the mirrors are basically useless.
But this should be celebrated because --- well --- it is sticking it to the megacorps! At least in a your imagination, if that is your dream.
Many of these stillborn mirrors will evaporate as soon as the hoster loses interest, which means by next Monday.