Neither of these "desktop infrastructures" are, or can, any time soon, represent "standard" systems that can be depended on by third-party tools.
Unfortunately, there is no "standards body" out there that can refuse changes to these systems due to the consideration that the change would break working code.
In this sense, they are both the same kind of "moving target" that has plagued certain other systems from a certain company in the northwest USA.
The point is that there is no guarantee (or way to establish a guarantee) that an application that worked with GNOME 0.25 will still work with GNOME 0.30. Ditto for KDE. The GnuCash project has suffered from challenges in getting their code to migrate to later versions of GNOME; not that it was problematic, but simply that it required a fair bit of effort.