First off, if the only publisher you have a problem with is Elsevier, you have already shown your hand. A half dozen other publishers are more expensive, but you can only name Elsevier. That means you're just repeating a meme that started on forums like this one. So take a moment and ask yourself why any of these publishers shouldn't take the same flak?
The "value" expensive publishers provide is clearly real, as customers are willing to pay for it. And there is clearly no monopoly; dozens of other publishers could make a similar journal at a lower price. Large publishers like Elsevier have thousands of journals, which isn't easy to replicate. But their profit is still in gold toilet territory. So why isn't a competitor able to take their business at lower profit? Answer: Prestige.
Louis Vouitton sells a handbag for $2k. Is it worth $2k? You could say no, that any other bag would be just as useful. But value isn't utility alone. People find that the bag is worth the price because of the prestige that the brand imbues the owner with.
Expensive publishers are still getting business because their customers still find value. Can you do it cheaper? Of course. Can you charge less profit? Of course. But will customers pay for it anyway? Of course. Because they're not paying for utility. They're paying for prestige.
Academic research is addicted to publishing in prestigious journals. Their entire system of grants and research positions is completely dependent on it. They simply have no alternative system. It's the industry dirty secret: prestigious journals are like coca cola with real coca leaf extract. You pay for it largely because you're dependent on it.
Of course, the customers complain about the price, so the question is, why not just buy something cheaper? Because that would defeat the whole point, which is to buy prestige. You can't just pay a kid in high school to run a web server for PDFs and say you have a prestigious journal. You have to have a brand that carries prestige, like that Louis Vouitton bag.
Until academic research no longer depends on prestige, no amount of walk-out stunts or individual universities walking out of deals will change anything. People still buy Louis Vouitton even though there are knockoffs. Because prestige is what they're buying, not a handbag.