Board Thread:Versus Debates/@comment-43403813-20190805194702/@comment-4080775-20190808211952

We do know it because Kamui's page says so, lol, and there is nothing else in the manga that would contradict it.

There is nothing that says the Rinnegan enhances a person's summoning abilities. It just has a path that specializes in summoning. Realistically, anyone in the Narutoverse can form a contract with a animal or a person. The Rinnegan can likely bypass this contract to where one ca summon something pierced with the Black Receivers.

But Kamui's page literally says Kamui is the only way in and out of the Dimension. Not to mention he had to be in a high area to maintain the best possible connection with the paths. This leads me to believe if you send them to another dimension, your control over them is pretty much screwed.