Background: an academic must publish. It is their purpose. And they have relatively little control over the venue they publish in - whatever happened some time ago controls where they can have impact and gain kudos (and reach).

I think the practices of publishers are immoral. A large system, including laws, the state, and various independent and dependent entities makes what they do legal, and disobeying their rules illegal. I was not forced to publish with Elsevier, but as mentioned above, neither did I have any realistic other options. Vested interests are real, however much we would like to wish them away.

To use an analogy: if bus companies were privately owned, and practiced segregation (and sitting in the wrong place could be construed as criminal), would it be civil disobedience to sit in the wrong place? After all, nobody is forcing you to ride a particular bus. You could get together with other like-minded people and form a new bus company. However, that is a serious undertaking; we could just make segregation illegal instead.

In the same way, we could form lots of new journals and conferences which would struggle to prominence; or we could make copyright assignment of academic work illegal, at least for publicly funded research. Don't forget that copyright is at the gift of the state; it is not a natural right but a constructed one; and without the state enforcing it would be significantly weaker.

Summary: Some acts are so immoral that the state makes them illegal, even between consenting entities. In my opinion, what one might call copyright theft, as practised by publishers upon academics, is one of those acts; yet currently the law says I am the one in the wrong. Hence, civil disobedience: active and professed refusal to follow a particular law because, like a bus, I have very little choice about which one to get on (to publish in), but I'll sit (put my paper) where I like once I'm on it.

As an academic, you are de facto forced to publish in certain journals that are considered to be important and of high quality. It is the collective status quo that does the forcing, as Robin_Message has already explained quite well.

(Coincidentally, most of my disagreement with most libertarians seems to come from the fact that they fail to understand or accept this relatively simple concept. If you implicitly assume that force and coercion can only ever come from the state, you're going to have a somewhat warped outlook on life.)

It's called "publish or perish," in other words your career as a researcher depends on you publishing papers in certain journals. Again, the fact that I have started to gain a reputation within my field makes no difference to my career as a researcher; only the papers I publish matter, and only if I publish those papers in certain venues.

"Presumably, if they wanted to do business with someone else they would do so."

So you are trying to apply a market-based solution to this situation, despite the fact that academic publishers remain in business because of a special government-granted monopoly? That's some interesting logic you have there.

"So what's the civil disobedience against? Where is the beef here, because I don't see it."

The civil disobedience is against a system that prevents the general public from accessing published research despite the widespread availability of a technology that can cheaply copy and transmit published research. I do not know if you noticed, but there is a global computer network available that is better at copying and distributing scientific articles than any publishing company has ever been, yet the majority of that system's users would have to pay more than their month's salary just to read the articles I cited in my last paper (or else more than a year's salary for subscription access). This situation exists solely because of copyright; there is no economic reason for it and it benefits nobody (other than academic publishing companies' investors).

Since you need it spelled out for you, here it is: the "beef" is with the fact that poor people are less able to access scientific publications than rich people. Traveling to the nearest university is expensive and time consuming, and even if you can do that there is no guarantee that the library will actually have a subscription to all journals (they almost certainly do not, and they may not care if someone who lacks affiliation requests a particular article or journal). We can correct that inequity, which works for the benefit of our supposedly democratic system and our supposedly capitalist economic system, by utilizing the most advanced and effective global communication system ever developed, and so the "beef" is really with our utter failure to do so for the sake of protecting businesses that were built around the communication technology of six centuries ago.