Using a pull buoy: helpful or damaging to technique??

hello! anybody knows wether using a pull buoy is helpful or damaging to technique?? I've read around the web that it might be actually bad to your technique as isolating the arm motion is unnatural and even though it can be a good as a workout does not help that much in terms of technique So i don't know if i should keep using a pull buoy on some of my workouts, what do you think?