from a brief look, it seems most of the benefits are attributed to antioxidants / other chemicals in the coffee, not caffeine.

I'm not a medical professional, but my understanding is that at least for the anti Alzheimer effect, it is due to the caffeine, specifically the effect it has on dilating capillaries in the brain.

Does that work with other stimulants? Pretty much all the stronger ones dialate capillaries with fewer side effects than caffeine

What other stimulants do you have in mind? Ephedrine?

Eg Dextroamphetamine is well studied. A dose that causes the same capillary dilation as caffeine would have undetectable side effects

Not for me. Coffee, anything caffeinated actually, makes me sick like I have the flu. The older I get, the more sensitive I become. I can't even eat chocolate anymore because of the caffeine content.

Did you ever investigate the underlying cause?

No, I just avoid it.

As the US Air Force once demonstrated, there is no such thing as the average man.

On average coffee is good, but you are not the average man.

Rabbit hole: designing flight controls that fit everyone turned out to fit no one

Tell this to GNOME developers

I think most people can drink only about 5 cups of coffee before getting various symptoms.

This is quite a low amount, i.e., we're frequently consuming it at a dose that is close to or higher than the dose where you see negative effects.

5 cups in which period?

Also, I don't think most people drink more than 2 cups of coffee per day -- if I know someone who drinks more than 2 or 3 I'd think they have a problem.

How many were not bought and paid for by coffee producers?