If you think constraints are a goal in itself, I don't know what to tell you. Constraints are a tool to generate geometry. If I make a design in Fusion360 or FreeCAD using constraints, and create an STL in the end to print, why would that be any different from using OpenSCAD and having variables in there to represent functional measurements? (and yes I've designed parts with constraints.) What are constraints but a tool for the operator to (visually) represent relationships between measurements? Variables and constraints are just different ways to express my model's measurements and locations in function of a set of fundamental inputs.
Is CSG less 'powerful' than brep? Of course it is. AI can do brep as well. Do you need constraints and solvers to do CAD? Of course not. I mean I'm not going to argue with shifted goalposts on what 'real' CAD is here, I don't care about what other people think about this. What I see is that AI is perfectly capable of making quite intricate 3d models today, passing people who argue about whether what the AI does is 'real' CAD left and right. Just like it passes those programmers who spends their days arguing that AI code is somehow inherently worse left and right. I don't care, I get results regardless of those people. What I meant with my original comment is that the assertions that AI today doesn't understand 3d relationships from 2d images is plain wrong, it understands it well enough to not only make 3d models, but to make it in ways a lot more conceptual than 'assemble triangles with skin()' (in OpenSCAD terms, but I had it do that in raw Python in models 6 months ago, when frontier models didn't have these spatial capabilities).