Earlier quoted context omitted.
The rest of the conference, sure. But the keynote has always been designed for a mainstream audience.
That wouldn't make sense. "Let's have a conference strictly for developers, but let's speak to a completely different audience in the keynote."
Despite technically being part of a developer conference, the intro keynote has always functioned more like a consumer-focused annual hardware and software update for Apple device users.
Hence things like the ever-present use of things like impressive-sounding "marketing benchmarks" that wouldn't pass as up to snuff on slides in a room of developers.
And also the very high level of abstraction so that non-technical users can understand the major updates — that's not exactly a trait one would use to describe a developer conference.