It turns out that Medvedev and Putin have spent the last 15 years trying to free Russia from its dependence on oil.
They failed, poor things, because 15 years is apparently far too little time. Prime Minister Medvedev said as much in an interview with German journalists:
But even though they failed, they still did a tremendous amount of work:
The lie was so blatant that Meduza published a special fact-check rebuttal:
The truth is that no one has done more than the Putin-Medvedev tandem to turn Russia into an "oil-and-gas slave."
So yes, it really is impossible to change the structure of an economy in 15 years—especially if you do everything possible to cement its status as a raw-materials appendage.
They are, of course, appalling crooks and liars. Since at least 2003, they have done absolutely nothing for structural economic reform—unless you count personal gravy-train vanity projects like "Skolkovo" (a state-backed innovation hub near Moscow). And now they have started singing the old tune: "we didn't have enough time".