It's accurate to say Firefox beat IE in that it freed the lock IE had on the web. By 2001 the majority of web browsers was IE6. Many parts of the web were being

It's accurate to say Firefox beat IE in that it freed the lock IE had on the web. By 2001 the majority of web browsers was IE6. Many parts of the web were being locked down behind IE/Windows specific features like ActiveX plugins and VBScript. Lots of intranet interfaces were built around IE6. It became as much a business staple as Microsoft Office. By the end of the 90s both Microsoft and Netscape had kind of given up on browser engines being performant and relegated complex/demanding UIs to native plug-ins. Anyone not wanting to use plug-ins (Java included) to make a web app had to use frame-based SSR which was very tricky to get right. Even when the design and implementation were good performance of the browser sucked. Firefox doubled down on performance of the rendering and JavaScript engines. Combined with XHR it was actually possible to make good web apps without using plug-ins of frame-y kludges. By not supporting ActiveX Firefox was also immune to whole classes of exploits ravaging IE at the time. Firefox breaking IE's hold on the web set the foundation for the rise of Chrome. Breaking IE's hold on the web meant at release WebKit on iOS and Android was a useful browser engine that could handle real websites rather than a bunch of broken plug-in icons or being limited to WAP/"Lite" sites like all previous mobile devices. A web requiring IE-only technologies like ActiveX and VBScript was never going to be accessible to mobile devices or non-Windows platforms.