There were many alpha and beta releases. The point was about finalizing API changes of kdelibs.
I did the same thing as the other poster, went to 4.x with KDE then promptly left as I fundamentally disagreed with so many of the things they were doing. I ended up at i3 and haven't looked back. KDE is a lot better than it was back in those days, but i3 is so perfect for me I'll never be a full time KDE user again. Not because I hate them, but because they're not i3.