Despite a rise in self-publishing, commercial publishers are still the main gatekeepers of what arrives on our bookshelves. As such, they have great cultural and – if a book takes off – economic power. A case decided in a US court this week provided an insight into just how much of that power is now concentrated in a small handful of multinational companies.

At issue was a planned merger of Simon & Schuster with Penguin Random House (PRH) – two of the so-called big five, which between them control 90% of the US publishing market, a fact not always obvious to the casual observer, as books usually carry on their spines the names of imprints, or subdivisions, of the parent company. PRH, itself the result of a mega-merger in 2013, runs about 300 imprints. Given the reach of these companies – PRH is active in more than 20 countries – the Department of Justice’s successful argument that the planned $2.2bn deal would “exert outsized influence over which books are published in the United States and how much authors are paid for their work” applies globally.

There was relief from many in the industry, from agents to author societies to the small independent publishers who already struggle to compete. There was also a cautious satisfaction that the arguments had focused on author earnings rather than solely on consumer choice. Some observers voiced the hope that the precedent could be extended to producers in other sectors – farmers, for example. The big five insist there is genuine competition between imprints for new properties. That may be true up to a point, but as Stephen King told the court: “You might as well say you’re going to have a husband and wife bidding against each other for the same house. It’s kind of ridiculous.” In Britain and the Commonwealth there is further concern about how many of the big five are run from the US. There is a growing sense that local taste, writers and priorities must be protected.

But there are dissenting voices, and undeniable complexities. Book publishing cannot these days be considered without Amazon; its huge sales mean it dictates terms often deleterious to both writers and publishers. PRH is dwarfed by Bezos’s behemoth but – having just reported nine-month revenues of ￡12.5bn, the highest in its history – it is better placed to push back than a smaller firm.

Consolidation also means that the practical requirements of publishing – including printing, distribution and publicity – can be rationalised in a world of battered supply chains and paper shortages. It may help to address the increasing difficulty (because of shrinking review space and internet-driven fragmentation) of building interest in new books. While the argument is often made that the multinationals are too aware of their bottom lines to publish more unexpected, not obviously commercial books, it can also be argued that deep pockets mean the big five can take risks that smaller publishers cannot, for fear of going under.

There is truth in all these arguments. But a multidimensional, confident publishing industry is central to a healthy society; the more multidimensional, the more healthy it can be. In that context, this week’s decision is welcome.