It's not for privacy's sake! I leave that to Privacy Badger.

I just prefer having pages load quickly and don't generally think custom fonts improve the experience.

Ah. I see. But doesn't blocking Google's CDN create all kinds of functionality problems on non-google sites.

Actually, it's only Google's sites I've seen it cause problems on, because some of their documentation makes use of icon fonts served from that CDN. Other sites have no problems in my experience. The font fallback works fine.