Well, I disagree. The first web client that OSM had been, of course, very different: there wasn't smooth scrolling, etc, which were added after Google Maps did

Well, I disagree. The first web client that OSM had been, of course, very different: there wasn't smooth scrolling, etc, which were added after Google Maps did it. However, a nice and smooth client with drag and zoom was a rather obvious thing to do: a lot of computer games had maps in them as early as in late 1980s, like Sim City and many others, where you could zoom, drag along etc, and it wasn't done in OSM rigth from the start mostly due to pitiful state of web browsers and web standards of the time. So I think that even without Google Maps, OSM would have evolved to have great usability, just as it did in our timeline.