It’s a perennial problem with all major FOSS projects and KDE is massive, it’s basically a given. At the time I followed it a bit more closely, there was clearly a churn of developers very similar to what JWZ described, with constant rewrites of entire applications because nobody had the time and inclination to maintain old ones (maintaining other people’s code is hard). Yes, the associated entities do a lot of good work, but it’s never enough - and realistically, nowhere near enough to be responsible for the entire Qt library.
Why not publish it for phones too? Something to do with UI polishing (widget arrangement, responsiveness)?
I have a phablet (6+ inches, high resolution and DPI) with pressure-sensitive stylus and I'd love to see Krita running on it, even if the UI is not optimized yet.
Yes, the UI isn't exactly the best thing even for tablets, so we refrained from releasing it for phones. Though you could always side load it once we have it in fdroid.