Yeah, that's what I see as the most likely explanation: it was a AAA game from some years ago.

The funny bit is that if indeed DRM was to blame, it actually results in less revenue for them: the pirate version packages ALL DLCs whilst I own just the base game and a few DLCs - without that problem I would've kept using the version I owned and probably buy more DLCs from them, but now I don't need to (PS: and aren't especially inclined to do either, since the official version doesn't even work for me). It's funny because DRM is claimed to help increase revenue rather than decrease it.