Yes, the Poly is always slightly awake and consuming battery, unless the battery is so low that the Poly switches off completely.
The rationale is simple - Poly always needs to be awake enough to 'listen' for bluetooth or wifi requests to reconnect to a phone/music streamer etc.
No denying that this ensures that owners (myself included) can get frustrated if they want to use Poly but discover that the battery is flat.
For some owners this represents a total showstopper, and a reason to sell the Poly.
I regard this as just a minor frustration. From a design point of view, the alternative to having the Poly awake all the time, is for Chord to have included an on/off switch, which would have disrupted the minimalist design of the outer case.
In conclusion, Poly will gradually lose charge, but only you can decide whether this is a showstopper.