It's not just Safari. The only times I really care about ad blocking are using the web with safari and Feedly and watching video. The content blocker also works with web view embedded in Feedly.

I very seldomly watch live ad supported video. I have ad free Hulu. For the two networks that aren't on Hulu - CW and CBS, I watch VOD from them via Plex. Because of the way that the Plex channels work, they skip the ads.