1. You are not OK with Shell dumping so much oil in the sea, so you stop buying Shell. But your action doesn't have any effect: you stop buying shell, oil still in the oceans. Boycott isn't the best path, unless it's really massive.

2. You are not OK with HP printer practices, but you don't necesarily want HP to go bankrupt or to pass a law banning HP practices. You just don't buy HP printers and you live happy afterwards. What other people does is not your problem. Boycott works.

You can say that HP selling ink subscription doesn't have any externalities, so every individual that buys one of such subscriptions is to blame and they don't shift costs to other people. You have options that keeps you safe from HP practices. Ask any Mac or Linux user how do they feel about Microsoft pushing trackers and ads on their OS: at best they don't care, but probably they laught at it.