Imagine each wire in your diagram is a resistor (which, practically, it is.) When you pass current through a resistor, you see a voltage drop.
The greater the current, the more the drop. The greater the resistance (that is, the longer the wire), also, the more the drop. That’s why this voltage is called an ‘IR drop’, as it’s proportional to both current and voltage, that is, E = IR.
When loads are wired in series (‘daisy chain’), the load currents add up in the wires, increasing the IR drop. And their wire resistances add up too, also increasing IR drop. Thus, the farther the load is down the loop, the more its IR drop.
Star wiring limits the drop to just the single home run from the power supply to each load. So the load currents don’t add up, nor do the wire resistances.
Your diagram doesn’t show a shared signal ground reference, but the nature of question implies one. So let’s clear that up. A ground loop is formed when a power return shifts from the ground reference, and there is some kind of path between that return and ground.
So if signal ground and power return are naïvely connected or related to each other within the devices, the return current will divide between the ‘return’ and ‘signal’ paths. That’s a ground loop, in a nutshell.
The star scheme reduces IR drop, and so will see less of a ground loop should it be an issue due to poor system design. But it doesn’t address the root cause: power supply return current making its way onto signal ground.
