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I think a fairly simple alternative explanation is that you unlock it at an exceptionally high level and it generally gets overshadowed as an attractive permanent-unlock by the AN-94. Same reason why you almost never see the Millimeter Scanner--players are usually prestiging away from it. I've always found it to be rather solid though.
... For art comes to you proposing frankly to give nothing but the highest quality to your moments as they pass, and simply for those moments' sake.