> When I graduated in 2007, it was common for tech companies to refuse to let their systems be used for war, and it was an ordinary thing when some of my graduating classmates refused to work at companies that did let their systems be used for war. Those refusals were on moral grounds.

I don't think it was very common really.

I think for the most part it was tech companies whose systems were not being used for war who like to boast that they refused to let their systems be used for war. Or that they creatively interpreted "for war" that since they were not actually manufacturing explosives, they could claim it was not for war.