There is a difference between the people saying they are done with Blizzard forever and those advocating for boycott. For those who believe Blizzard is beyond redemption, I agree; cancelling your subscription and uninstalling are empty threats. Deleting their accounts is the only way to effectively back up their words with meaningful action.
Boycotting implies that you are withholding your commerce unless and until the business meets certain conditions or demands. In which case, cancelling your subscription makes more sense.