However it's slowing changing. Knoppix has always been seen as a trend setter, and it still has a large influence where it matters - open source maintainers that are not corporate-driven (i.e. Debian).
Knoppix hasn't been seen as a trendsetter in an extremely long time that I know of. I remember it being a big deal before live CDs became a thing that everyone did, but that's about it.
I don't know where you're seeing this trend, really. For all major distros, it's been the opposite thus far.