Booleans and sub-d still works if for example you can round edges later by hand or simulate a NURBS workflow and later convert the sub-d into NURBS patches to trim and blend everything.
Problem with sub-D is it’s own nature. Hard surface modeling is possible but not always the best.
Till today I did not see a car that has clean and manageable topology made with polys.
Yes you can with care and time build a perfect car put the poly count will be painful and checking curvature a problem.
If then a detail has to be adjusted you basically face to restart or exercise yourself in the art in time consume vertex adjustments to maintain surface curvature flows.
However you can perfectly use sub-d to sculpt the main shells and use boolean to do detail work and later in a NURBS system do you assembly.
NURBS and sub-D to a certain degree work / behave the same way with the exception that NURBS can be precision trimmed without changing the curvature while when adding a hole into a sub-d mesh the surface deforms and you get typical sub-d topology artifacts. Sub-d on the other side allows arbitrary topology like extruding a face and having the blend surface right there which does not work with NURBS at all.
Years ago NURBS or sub-d where not compatible with each other. Since Maya and specifically T-Splines that is the past.
For my product design I utilize sub-d modeling together with NURBS and end up with perfect models.
While the end model will be pure NURBS Blender with sub-D and booleans are a great combination to build model mock-ups and explore design ideas because how fast the booleans can work on a simple sub-d mesh.
While NURBS is more precise the workflow is slow and the booleans allow me to move the object by hand and see the result quite instantly.
In Alias it would involve more steps. In Rhino it will require many undos lol …
It is a question of workflow.
But yes maybe for character modelers booleans might not be the best idea because currently you cannot bevel the sharp cut edge.