Oh, I am sure we would have gone similar places without him... eventually. A windowing graphical user interface is objectively easier to use for most people than alternatives at the time, for example. But he saw it at Xerox, recognized it for what it was, refined it until it was sharp and crisp, and made such an impression that everyone followed suit. How long would it have taken otherwise? How many failed attempts and how many iterations? How many more failed tablets and how many more incremental improvements on feature phones? It's not like it only happened once.

Anyway, you may very well disagree. I was just trying to explain why some people who think differently might be more than a little sad about it. And that just because he was a stranger doesn't limit the amount of sadness people may legitimately feel.