KDE has the extra layer of Qt in between. That brings a load of benefits thanks to an array of paid professional hands developing the toolkit, but the downside

KDE has the extra layer of Qt in between. That brings a load of benefits thanks to an array of paid professional hands developing the toolkit, but the downside of course is that some of the issues just have to be fixed on the Qt level. For example, it took a while before the multi-screen support in Qt 5 was mature enough to provide a stable foundation for a desktop environment. I'm sure KDE could solve these problems somehow in-house too, but the fact is that development power is limited so it makes all the sense to solve the issues in the correct layer in the first place.