Besides maintaining the eponymous desktop environment, KDE is very much a platform, leveraging Qt, but also offering its own core libs and infrastructure for tons of stuff.
So much so, in fact, that the title of their webpage is: "KDE - The KDE development platform".
I should know, I've been following (and occasionally participating) in the project since 1998.
It is not a platform in the sense that's meant in the post above, which is why I said the article is misleading, not wrong.
Like you said, KDE leverages Qt. Qt doesn't leverage KDE in the sense that "Qt's native platform is KDE".
When you say "native" when talking about a cross-platform toolkit, you're implying the toolkit was first designed to run on that platform and then ported to others. Qt predates KDE, as you well know.
>When you say "native" when talking about a cross-platform toolkit, you're implying the toolkit was first designed to run on that platform and then ported to others.
No, you're just implying (as the parent did) that the platform (KDE) had picked and stuck to the toolkit (Qt) as its basis, unlike Wx which has multiple.
So much so, in fact, that the title of their webpage is: "KDE - The KDE development platform".
I should know, I've been following (and occasionally participating) in the project since 1998.