My dad worked at Exxon for his entire career and I have some knowledge with this from my science background. Not that I'm an expert, but do have a little insight.
Octane is basically ignition vs performance. 87 ignites easier but doesn't offer as good of performance. 93 is harder to ignite but offers better performance. It may have made a difference putting 93 octane in cars back in the 70's & 80's as it kept the engine cleaner and running better. Now-a-days with computer controlled fuel injection instead of carburetors its more about engine design. If you have a performance sports car or similar that's designed for 93 octane then that's what you should be putting in it. Most cars on the road do just fine with 87 so anything more becomes a waste of money. That said, whatever you started putting in your vehicle you should stick with it because that's what the engine broke in with using.
One caveat of this... I'm not a car guy so y'all likely have a better understanding than me on that side of the fence. I only have my insight on the fuel side of things.