It is, though. Safari has native support for 3rd party adblockers, it’s just that many people don’t know. AdGuard is one of the good options. Safari is doing the actual blocking for the most part (the extension just hands over the filterlists), but nowadays some of the adblockers include an optional extension that applies some rules for complex ads that are not supported by the Apple API, such as on YouTube. As an end user you just have to install and enable the adblocker.
Then there are also other browsers available with built-in adblockers. Admittedly those are all limited in some ways because they’re forced to use the same browser engine (outside of the EU), but they are very effective at blocking ads.
They also point out the main differences between the two voices in the paragraphs below this quote. I do believe that they hired a voice actress and that they didn’t train on SJ’s voice, or at least not entirely. However, I wouldn’t be surprised if there was big push for finding a voice similar to SJ’s voice in Her, no matter how much they deny this.