In SWI for example, clpfd and friends rely on attribute values and hook predicates to interject the backtracking process with their own thing. SWI provides those things so that it can be extended.
Non trivial Prolog programs which only use pure predicates and do not use cut are sparse. Yet those are also the only circumstances in which things like clpfd will work without special consideration.
Besides pengines and web development I have very little experience with SWI specifically.
And, well, yeah, it's common (e.g. look for cuts in https://github.com/mthom/scryer-prolog/blob/master/src/lib/c... ), but I don't think I've ever written a cut and I use Prolog rather effectively as a tool for problem solving. It's an interesting and quite powerful way to model and examine problems even if I don't produce programs with 'imperative' interfaces. Some scripting tasks are also quite easy in Prolog, e.g. certain log parsing, stuff like that.
Non trivial Prolog programs which only use pure predicates and do not use cut are sparse. Yet those are also the only circumstances in which things like clpfd will work without special consideration.