It’s significant because it’s really not. Fortnite didn’t beat Google, beating would mean that actually Google had tried to stop this rather than provide a feature to go beyond the playstore.
It would be meaningful if this was a method to be replicated elsewhere when in fact it isn’t. Apple doesn’t provide a similar feature that allows installing apps outside its store. There is no way to make Apple do that and in fact it’s something that many appreciate in Apple since it is in part what makes the platform a bit safer (don’t forget that the very possibility of enabling third party apk installation is what lost Google partners contracts to provide devices to be used in government agencies).
It’s good that Fornite proved you don’t need the play store and it’s environment to succeed but that’s a lot thanks to its willing to invest in marketing. It’s not like a garage dev is going to be able to shell enough to market his own website well enough to convince people to install an app from an unsactioned source. It’s more likely that an app will be found randomly browsing the store than randomly finding a site on the web.