Apple deserves a lot of credit for their support for WebKit, particularly in its early days. But even old time apple webkit devs will readily admit that the existence of Mozilla made WebKit much more viable back in the day. Mac's had practically no marketshare during those days. The fact that Mozilla existed and had a reasonable amount of marketshare across platforms made it possible for Apple to ship anything other than IE as a default browser on Mac. Mozilla maintained the incentive for webdevs to support non-IE browsers, and use standards-compliant CSS. Desktop Safari as a default browser would not have been a viable product if so many webdevs had not already worked to make their sites work well with Gecko/Firefox. Webkit sends "like Gecko" in its user-agent string for a very good reason.

In other words, a lot of the web kept using standards (and not IE proprietary stuff) since they wanted to work in Mozilla browsers. And all of this content tended to also work well in webkit as well. This made Safari useful and viable. So, its at least somewhat reasonable to say that Mozilla and Firefox are perhaps primarily responsible for keeping the desktop browser market open for non-IE products. Their existence and marketshare allowed the newer browsers to compete on the basis features and performance and not be hobbled by poor website compatibility.

Just fine. It wasn't WebKit that helped prop up web standards. It was Mozilla.

In the same place ... the webkit revolution started with V8 when we saw how fast web stuff and javascript can be. As long as there was any kind of layout engine for google to stitch their VM to the revolution would have happened.