Is this just a feature of piracy?

Nope! It's just that the only way to acquire a movie exclusively released at the cinemas requires people to go there and record it with their phones/cameras, and since you can get caught and fined for doing that, the only people doing it nowadays are those sponsored by those super shady betting websites... fair enough I suppose.
Once the movie makes its way to streaming services (or to Bluray/DVD) you'll be able to get a high quality copy without any crap baked in.

Now, specifically about Saw X: There are rumors it will hit Streaming sometime in October, but I haven't found a reliable source to quote about this.
If you are absolutely DYING to watch it, there's the "Will1869" release, which has all the ads removed, but unfortunately has a watermark bouncing around on the screen.
There's also the "Telesync.x264.Dual.YG" release, it comes with dual English/Spanish audio, has no watermarks and a single, audio-only ad on one of the quieter scenes, but has rather muffled audio and the post-credit scene is in awful quality, so.... unless you can live with the watermark or the muffled audio you might just have to wait until the Streaming release comes. Hope this helps!