Not keeping promises is not the system's fault. People do it all the time in very different environments. When the context of the promise changes significantly, it tries the resolve behind the promise, and it's natural, almost expected, that people break it. Capitalism is almost orthogonal to this phenomenon. Of course, in a capitalist society, you'll see a lot of examples of capitalist entities making the bad stuff. But if we organized things in a different way, then different entities would be doing very similar things.