Since Obito can travel through space-time, I wonder why he didn't just teleport to all those jinchuuriki? He could then easily bring them to an Akatsuki hideout where the combined force of them could capture them without others interfering.
The answer is because of the nature of his jutsu. His jutsu works by moving whole or part of his body into the other space. His jutsu has a weakness in that the bigger the object he is transporting, the longer the time needed for him to do it. This was noted by Konan and was mentioned during the fight between Konan and Tobi when the latter was about to retrieve the Rinnegan from Nagato's corpse. If I remember correctly, to move his entire body he needs about 5 seconds.
Now add another person to the equation and you get 10 whole seconds before he can do the jutsu successfully. 10 seconds next to a Jinchuuriki that knows you're going to kill him. There's no way they're just going to sit tight and enjoy the trip. So this makes kidnapping the Jinchuuriki and ganging up on them at the hideout like you're suggesting as an impossible thing to do.