Most crimes committed by US citizens in foreign countries are in the context of their military service: War crimes. And instead of being incarcerated for those, they just complete their tour of duty and go home. With any luck there's some public outcry about their crimes, but often not even that. The US is also not party to the Rome statute (https://en.wikipedia.org/wiki/Rome_Statute), and has even threatened to personally target International Criminal Court employees if they try to prosecute US citizens.

... but I suppose you're right about more mundane, non-government-sanctioned crimes.

I do believe it. But that's not relevant, because OP is talking about an additional power.

In that case the argument should be about whether or not it should be a criminal offense at all (meaning whether European CEOs should be jailed in the case of malicious actions against their users). The fact it would theoretically extend to people in the US (good luck extraditing them) is IMHO not really an important thing to consider.

Well, that was the example this thread was talking about. You could change the topic and make what we were talking about unimportant, but that seems a bit churlish to phrase it that way : - )