That it CAN be a problem depending on the choice of plant(s) placed next to the block - in the short-term.
In the long-term you are right - Its just fine.
I had to address this because I have killed plants with this method....
Albeit, it also depends on the actual source of raw material for the said "Cinder Block" as the quality does vary from region to region.
And the Humic Acid from the decaying wood absorbs the Lime and gives the correct pH in the short-term.