That was probably the case back in vanilla (pre-expansion) WoW. With the introduction of cross-realm battlegrounds in 1.12 - a month before the first expansion - followed by the activation of arenas in the first expansion, they most likely considerably expanded their server capacity to accommodate for the increased load. I remember seeing news articles back in the day just a few months before Burning Crusade's launch that Blizzard had bought a massive amount of servers, but the only thing I can find now is this blog post: http://www.rahulsood.com/2006/02/blizzard-going-crazy-for-op...

However, it's important to note that around this time Blizzard was heavily improving their Battle.NET service and launched a download service where you could register your CD keys from their previous games such as Starcraft and Warcraft III and download a fully working ISO that did not require the physical CD to run. The server purchases may have gone towards that instead.

Would love it if Blizzard wasn't so secretive about everything, especially their tech. CCP, makers of Eve Online, have been very forthcoming in talking about their entire stack in their developer blogs and videos - from infrastructure and hardware, to how they profile their code and the software design choices they make.

The market for private WoW servers in the past has been a major concern for Blizzard and I'd imagine has been a large motivator in their decision to closely guard their infrastructure design.

No, they just sold 4 blades per realm for a charity auction.

A few months later the used equipment market was flooded with the same blades, so I imagine they offloaded quite a bit of hardware.

I wonder how many blades per realm they use now with the new continents and whatnot.

That's exactly what he says on the web page. :)