It does happen just like bloated management also makes a company less flexible even though managers don't want the company to fail.
They wouldn't intentionally push it to fail, but they could easily push it very close to failing and then something else pushes it over the edge, happens time and time again.
I was under the impression that in recent times unions had been mostly disbanded, with any remaining being in government that can't fail like a business can. You might have a fair point that we've started seeing a return of them in the last few years (article being an example of such), but it seems much too soon to see them rise up to have the power spoken of in this thread. That only happens as the union becomes more and more comfortable pushing back.
Am I misinformed — that unions have actually been popular in the private sector over the past long while in order to trigger what you speak of recently?
They wouldn't intentionally push it to fail, but they could easily push it very close to failing and then something else pushes it over the edge, happens time and time again.