Unfortunately the triplet DE--GUI-Toolkit--Applications is often intertwined or at least evolves in the same manner.
For example, I don't want GTK-3, I only have GTK-2 installed. It could be all fine and dandy if, one after another, year after year, applications wouldn't give up their GTK-2 backend to only maintain/develop their GTK-3 one. The set of (up-to-date) applications I can run decreases, despite the fact that, as Alxlaz, I still run WindowMaker :-)
On Qt side, there are applications which requires an exact version of Qt (not only the main version Qt-3/4/5, but the point version), or require KDE, or require an exact version of KDE. If you want to install a new application, you have to go back in its history and find a version of the application that matches your installed library version. Or install another Qt version and hope it doesn't break other programs.
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A bit different, but many years after my last try, I tried to use Scribus. I quickly remembered why I had not really used it long the previous time: text input is still convoluted and not WYSIWYG, which is a bit annoying (understatement) for this kind of program where you precisely want to see how text flows. So I gave a try to the new branch (which BTW required a new version of Qt, if I am not mistaken), hoping that they finally did something about it after all those years this program exists. Alas! Apart from the underneath Qt version change, the visible changes were: icons are now flat and monochrome (i.e. you cannot recognise one from another), keyboard shortcuts have been slightly and viciously modified (what was F3 is now F4, stuff like that... but why, oh why? what is the freaking point of doing that?), and it crashed on me after 5 minutes.
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So basically, even if you'd just wish to have a few bugs fixed, and possibly a long-time missing feature finally added, by getting the new version that does this, you are forced to follow the crazy flow of adding or updating all libraries/toolkits/environments, because maintainers have decided it was way more interesting to rewrite their stuff for the umpteenth time with a different/new back-end (toolkit, environment), rather than polishing their existing, mostly fine for the job, code base.
It is exhausting, I am, too, really tired with that churn and constant breaking.