When the company's immune to accountability [...] backlash changes nothing.

Not really. Backlash is important because it shows there's an alternative. And not to the company - the company won't change. But its users, customers and consumers just might.

It creates publicity, which triggers people to talk and think about the issue.

Which is a good thing as well as a driver of change.

Boycotts are also effective. The only problem is, huge companies have their fingers in multiple jars (industries, brands, etc.) and their main customers are other companies.

This gives them a great dose of stability. But if people were to suddenly boycott all of say Nestle's brands, stores wouldn't order new Nestle stock.

There's also no need for extreme backlash in some cases. Just look at Walmart or Microsoft.

Microsoft is bleeding users at a record rate. Sure, the year of the Linux desktop is still not here, but Linux market share has been rising dramatically lately. Why?

Because Microsoft keeps shooting itself in the foot.

Walmart is a similar story.

There's something about huge consumer-facing companies that makes them extremely vulnerable to losing focus and falling out with consumers.

If some more Boeings fell out of the sky and not just one or two a few years ago, airlines would be looking to clear thenselves of all Boeing stock. This wouldn't even need backlash.

Backlash is a source of bad PR. And bad PR causes customer loss. That's profit loss. That's a bad credit score. Hell, even the government might take a look and find some issues they'd like to check out!

As you can see, this can all spiral out of proportion.

And backlash is the first step in this story.