I recently got a nice office chair for Christmas with heated massage functionality and it uses a barrel plug to power it but I have to be super careful to not pull it or damage the barrel connector in any way. I wish there was a magnet conector for these things in case of a yank pull and was wondering if anyone had heard of some adapter like the one I pictured above.
Any type of connector can be magnetic like that. But like the other guys said, it's a question of quality - lots of these third party connectors are pretty shit.
Also, it adds resistance to the connection. A quality magnetic connector should have minimal resistance. But a crappy connector? Who knows.
More resistance = more heat + potentially insufficient power transfer.