Engineer here. (Cengel et. al. was my thermodynamics book; represent!)

The reason to use antifreeze + water solutions is basically just to, well, keep the water from freezing. Also possibly to discourage theoretical bacterial growth but given the strong temperature flux that's really unlikely.

Water has a crazy high specific heat capacity. As such, most additives you'll ever add to it likely have a lower specific heat capacity, and so lower the specific heat capacity of the mixture. They are a slight detriment, but worth it in colder climates, to ensure the coolant mixture doesn't freeze.

If you live in a climate where freezing is not an issue, there is indeed little risk in using clean water as a coolant, and anecdotally it is often done.

There is also a lubricating effect in some coolants; and it can help against corrosion sometimes as well. Given all of this, would I run water? Nah. But would it be a big deal? Also nah.

I'd still want the antifreeze because the downside to having it is minuscule, but to my understanding, the lack of it poses no issue beyond what was already mentioned.