I would argue that it does matter for the brain. The large number of variations on the large number of different types of receptors means a great amount of variation in adaptability of the neural circuits to a great number of edge cases. But it also means there's a lot of possibility for maladaptation, such as with some presentations of mental and non-mental illnesses. Neural circuits can "remember" firing patterns through some of the varying adaptations, and not all circuit memories have the same function or the same effect.
The parent comment about varying transistor combinations was not quote correct in my opinion, as these variations in receptor makeups DO change how the neuron and circuits respond to stimuli.
This makes sense to me. It's like we're peering into a portion of the main logic in a function with one frozen global state and ignoring the idea that there are zillion global variables that can alter that logic.
Needless complexity has costs associated with building it and maintaining/running it, so I'd expect in the majority of cases it would be selected against strongly enough to disappear over time. Which implies the majority of complex systems are complex for a reason, because if a cheaper less complicated equivalent was equally good then that would win out.
Biological matter can't exactly opt out of being made of jiggly proteins immersed in water. And nerves can't opt out of the million things a cell needs to do to maintain itself. That's the kind of thing that adds immense complexity whether it's useful or not.
The parent comment about varying transistor combinations was not quote correct in my opinion, as these variations in receptor makeups DO change how the neuron and circuits respond to stimuli.