I'm not so sure myself anymore, either. Looking at the MDN notes on it, I now realize that addEventListener() approach works on all sane browsers (with the note that IE versions prior to 9 are special flowers, and need shimming).
Rather than reminescing how stuff worked a decade to decade and a half ago, I should read up on it. I'm just lazy. I now know that I can use the easy approach for UI events across all browsers (I'd be happy to exclude IE versions prior to 9.0, adding shims only if asked+needed).
Right. I am still not up to date on browsers and Javascript, but it is already clear that the places where workarounds and shims are needed, have changed. For the better, I think.