When companies do this, as well as suppliers getting shafted quite often the sub-contractor trades are getting shafted too. If the subbies get wind of this during the build, quality can drop considerably – morally wrong but understandable. I’ve heard of drains being plugged with concrete, roof tiles laid without a single fixing. Yes the NHBC would be the backstop, but do you want a potentially protracted claim & it’s only a structural warranty, so there’s potential for a lot of issues that aren’t covered by any warranty.