This is what happens
Standard USB wire can be at most 2 meters long. This is the absolute maximum for this standard. Longer ones won't work in most cases. Not only for charging, but for any data operations.
Sony provides shorter cables because any longer will cause electromagnetic inductions within the wire (kind of electrical noise). The only way to minimize this is to put ferrite cores on both sides of the cable. You might seen them before, they are bold rings over the wire very close to the plugs. This helps a lot only if the whole cable is not longer than 2 meters.
USB cable with those cores are more expensive than those cheap Chinese. But even if they are longer than 2 meters there is no guarantee they'll work with every devices, especially with those sensitive. Keep in mind that this is suppose to be data cable and it shares both charging and data functions. So they are built to handle the charging in more "electronic" way.
This is not that weaker charger can't provide enough juice, at this level of current and voltage it doesn't matter if the cable has 0.5 or 10 meters, but this "noise" can make a big difference. You can check this by connecting the phone to the dock with this long one (if you can), or use some long extension cord. It will charge like a charm even with long one, because this socket in the phone is not designed to handle data, it "doesn't care". But still in the time of connecting the phone to the charger with such a long cable can make this induction thing and if the cable doesn't have ferrite cores installed - this most likely will be fatal for the phone.
The other thing that might be a problem is that the cable itself is designed for data connections and have shorted pins inside one of the plugs. As a result of this it (theoretically) may be causing some extra electric load and with a length of it this could make problems.
Long USB cables always mean trouble. Especially with sensitive devices. Long ones, on the other hand, are very expensive, not worth using them only for the charging process.
Of course you can risk highly power efficient charger (like 3A or more) to force some current stabilization but in the moment the induction problem comes to play, the "stronger" charger is, the louder "fireworks" will be.
