The good thing with online bullies is that they often don't have all that much power. You can be content to ignore them. And sure, maybe sometimes a sharp reply is needed, but stick to the facts, don't get dragged into the mud.
The problem is that these so-called bullies are hurtful to the community. The concept of computing or technology in general is frightening to most because of the apparent "requirements" in terms of knowledge one needs to have to participate in the scene. Browsing the Github repository of your favorite open source application can be overwhelming to inexperienced people, and if you pair this fear newcomers have with a toxic community, the effects can be disastrous.
The good thing is that these "bullies" are a tiny minority. Yes, they are very vocal, but it seems that no one stands up to them (or maybe just chooses to ignore them). Ultimately it varies from community to community.