I've been a long time KDE user - since the 2.x days, though I started using it more seriously when 3 was released, and I still use it daily both at work and at home. There's no denying that the transition from 3 -> 4 and 4 -> 5 were difficult. In the first instance it was clearly a rush to get things out before they were ready. In the latter case it wasn't quite the same, though some functionality did regress due to rewriting - but there was an added dimension of KDE relying more on Qt's inbuilt functionality instead of its own libraries, but unfortunately they weren't quite ready (or complete) yet. Multi-screen and session restore in particular were broken for quite a while in various ways. Both are mostly fixed now, which is good because I rely on them heavily; in the interim I just made do - unfortunately I know not everyone was prepared to do that.
I do follow dot.kde.org and there are definitely passionate people still working on KDE - even some who have been around since the old days, though sadly many have drifted away. It would be nice if this article had a positive effect and brought some attention back on KDE. in any case as a user I won't be giving up on KDE any time soon - as I type I have Konsole, Kate, Konversation, Okular and Kontact (4.x version) open and I would have a hard time using alternatives to any of these.