Projects always struggle with this—development is always miles ahead. But, hey, look on the bright side: it's a great way to contribute back.
Which question was not answered?
Also, not to be harsh, but your comment is borderline violating KDE's CoC. if the volunteers working for free helping out other people do not know the answer to your question, there is not much anybody can do about that 🤷. It does not mean other questions will not be answered.
My guess is that they had been developing the new version of SteamOS from before 6.3.3 was available and the newest version of Plasma was not ready in time, and that they were always going to prefer to go with something they had stabilised than risking putting a newer, less tested version of Plasma on a commercial device.
If you don't get the answer you are looking for here, get yourself to our Discuss forum. Devs hang out there often and they may be able to help you.
Yeah. Muscle memory and so on—it is so hard to split from years of doing stuff a certain way. Keep at it! We are all rooting for you.
Yes. If the cursor is sluggish, there is something wrong. Get yourself to https://discuss.kde.org and ask there.
In many cases the default is chosen because the people placing the order don't know any better. An educated staff can help them make better choices.
It's free. Go try it for yourself. There's nobody better than you to see if it adapts well to your workflow and projects.