I mean, it's not if they have some sort of sci-fi solution to trivialize the vastness of space. But it's a schelp beyond most people's comprehension to haul a meaningful amount of anything even to the next star system over, much less to a distant one, under any propulsion method conforming to the known laws of physics. Alpha Centauri is 25 trillion miles away. And that's nextdoor on the galactic scale. We might be able to turn that into a journey of mere decades someday, and might even take that journey, but the hop around the galaxy sort of travel of so much sci-fi media is just orders of magnitude beyond what could probably ever be possible. Trivializing the vast energy requirements also requires tech well beyond ours, but within the realm of the plausible under how we believe the universe to work. But having intersteller travel take place on a time-scale where "exploitation" is reasonable as a principal goal, is probably always going to remain science fiction. It requires different rules of physics from those which to the best of our knowledge exist, which is rather different than just requiring more advanced tech.
I suppose if they were a species that regularly went into hundred year hibernations during which they consumed little or no resources then some of them might be itinerant between the stars for reasons of material exploitation. A generational colony ship situation seems plausible enough as well and would also qualify as a form of exploitation. Really there are a variety of ways in which another species might have a different relationship with time, which could change the calculus. But generally exploitation of the type for which humans have historically sought out distant lands is not practicable in the absence of some sort of (preferably much) faster than light travel.