Control theory diagram for feedback circuit with compensation
I think this tells the story a little more accurately. It is almost identical to your first diagram, but you can't just connect outputs of blocks together. This creates an impossible condition -- two outputs defining one signal without any kind of defining operator. They need to be summed, and this diagram illustrates that.







simulate this circuit &ndash; Schematic created using CircuitLab

Another way to represent this would be to combine the op amp input summer and the negative input summing node into a (+ - -) summing operator, but circuit lab doesn't seem to have that.