The criteria for excusivity are indeed flexible, here’s another example:
This model was created using this OpenSCAD script: https://www.printables.com/model/92976-christmas-tree
Just change 3 parameters ($baseRadius=10; $trunkHeightWished=8; $fa = 15;) and you get pretty much the same thing - but not identical, because the script uses random numbers for branch orientations and lengths.
V2 is the same tree but with added decorations - which were stolen from Christmas Tree by BQEducacion - Thingiverse, the star was smoothed though.
V3 is just some more sizes, thanks to the OpenSCAD script, including the same star.
All three are copyright infringements, all three are exclusive models, and all three copyright infringement cases have been declined.
Note that copyright covers an artistic expression of an idea, not only the exact copy of a thing: If I took a song and re-recorded it with the same instruments, maybe changed a word here and there and tried to sell that, the audio file would have completely different bits&bytes, but it still would be copyright infringement. So even if that person created those trees from scratch (which I highly doubt) but to a level of similarity that makes them indistinguishable from the original, it’s copyright infringement. And of course it’s not the level of originality that MakerWorld says is expected from exclusive models.
My personal conclusions:
I’ll not publish parametric OpenSCAD models, just a few STLs, unless I don’t care about that model much.
Secondly, I’ll not publish exclusive models any more (I have 2), it’s bad for the community.
The exclusive model program gives more incentives.
Incentives are a path to the dark side. Incentives lead to greed, greed leads to copyright infringement, copyright infringement leads to suffering - as Yoda said (or something similar).