Like do they actually, reliably effect change in the way the activists intend?
Have they worked against Israel? Did they work against Apartheid South Africa? Could they work against Trump’s America?
My hunch is that they don’t, really, but can be a useful promotional tool for other issues. Like don’t buy American is a simple message. If people will listen to that, they may listen to reasons why, which maybe could build a movement.
But on the whole I am very sceptical, and would be interested in any reasons for or against boycotts.
Also because Colbert previously was cancelled and that was already upsetting to many people. If Colbert wasn’t cancelled already We might not have seen enough people care when Kimmel was suspended