Why are adults expected to be so loyal to the companies they work for without any reciprocity from the companies?

I wrote a post on this topic in my local Facebook group and it got removed in under 5 minutes so I'll try here. Both my husband and I have been told by our parents and others that we "owe" a certain level of loyalty to the companies we work for. My husband has been with his company for 10 years and I've been with mine for 13 years. My husband was promised a big promotion at his job last year that he never got. He was asked to train a new employee so that it could be done by "the fall" and we are now entering winter. He has been told that the man he works for is close to retirement but it has been said for at least 5 years that he is close to retirement. There is a chance that my company could close my facility in the next few years because we are a smaller facility in terms of square footage and number of employees. I recognize that companies aren't legally required to be loyal to employees, but why is it wrong for employees to not be loyal to employers at this point? What level of loyalty should employees have for their employers and why?