Ranked unfairness

Why is it possible to start playing ranked so late (1-2 months) before seasons end and still get the best rewards? I read somewhere that Riot wants it so that highest tier players are active the whole season. This doesn't make sense at all and I want a Rioter's comment right here. I've played over 1000 SoloQ games already, used my best energy and feel like I've proven I deserve Challenger rewards but still have to play just because this banked system plus there is an exact date when the season ends for everyone.

Next season I won't be doing the same mistake and just spam a few games in autumn if this retardness is not changed.