The transition from KDE 3 to 4 was a completely disaster, but KDE devs learnt from it. They made a successful transition from KDE 4 to 5, and are committed to

The transition from KDE 3 to 4 was a completely disaster, but KDE devs learnt from it. They made a successful transition from KDE 4 to 5, and are committed to users needs, so we can expect a smoothly transition to Plasma 6. Now, compare it to Gnome, where every release means deeply changes for both users and 3rd party developers, and Gnome developers simply don't care.