The actual guilt trip is that this is cheaper for the manufacturer, so they buy the cobalt from there. The DRC has along history of enslaving its people for whatever money they can get.
There are other sources, but the producers would rather pay the cheaper price. Except for Apple who banned buying from there.
“Except for Apple who banned buying from there.”
And that’s my point. Customers start getting picky, and capitalism responds by improving working conditions.