We certainly didn’t intend to cause any confusion by this. That App Store section shows what RW8 was tested on and is compatible with. We always recommend running the latest version of MacOS (usually), especially since RapidWeaver 8 was developed on more recent versions of MacOS.
That said, we have a handful of users who run dozens of sites with RW8 on 10.11 and have no issues. Think of it as “it works with 10.11”, but “10.12 is recommended”. That’s all. 