On Preferences --> Shields, add an option to block web fonts and use system fonts instead.
This feature have 3 main reasons:
1 - Speed
Avoiding download web fonts will increase page load speed for users.
2 - Reduce data usage
Users do not always care to pay for bandwidth used to download mere aesthetics such as fonts.
3 - Privacy
Third-party delivery networks such as Google Web Fonts or Adobe TypeKit can have the ability of profiling your browser to track what sites you visit, building a valuable profile about you that they could sell to marketers.