Does it make any difference to you than a large majority of the issues
weren't actually kde ones, but bugs in other components of the graphics
stack?
Well, first of all my issue still exists...so until it's resolved it is debatable what the issue is...
Second, reports of these issues keep coming in, so they aren't resolved.
Third, my observation is that these issues only are encountered with Plasma5. As I mentioned earlier, I don't have issues with GNOME or LXQt with KWin.
So regardless of the cause, it is a Plasma5 issue if it is only occurring with Plasma5 - and if I were on the Plasma5 team I would be aggressively working with whomever to ensure these issues were resolved. If its a matter of hardware acceleration, the end user should have an easy method to turn it off. If there exist such incompatibility it shouldn't have been mainstreamed. All this has done is given Plasma5 a bad name.