[bawolff]

Difficulty and block rewards are separate things. There is no contradiction here.

Block reward stays constant, amount of work required (on average) to get a block reward is dynamic in order to make it so that total number of rewards given out over a length of time stays roughly constant.

So if too many block rewards are claimed in a given time frame, difficulty is increased to slow things down. If not enough are claimed then difficulty decreases to make it easier to get one.