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.
If it’s a company selling a product an effective boycott of 30% or more of their customers would work under extended period’s of time.
For military you have to go to war against them. You don’t ask Israel to stop killing you. You pull out the uno reverse