Unless you can’t buy those books elsewhere for competitive prices, this is fairly meaningless.
Britain is well known for it’s closet socialism.
To add, I don’t disagree with your premise in theory, but the example you’re using is more like someone arguing they’re fat because the cookie maker keeps making delicious cookies and selling them. They are making a choice, they have a choice.
There are probably better examples of companies that could/should be checked for their cornering of the market and subsequent influence, Facebook for example, you’d have a better chance in court. But how good?..still not good probably.
Is this like an argument people are so entrenched into facebook, or apple’s or amazon’s ecosystem for example, that it’s not fair? That they have no other option?
I dunno, I think things have to go pretty far before you can seriously talk about breaking these guys up, legally. You can’t exactly do it pre-emptively either.