The thing is, your employer probably does not feel loyalty towards you. Protecting yourself is the real reason.
Loyalty is not a black and white thing.
I can list close to 15 years of small experiences that make me feel like my current employer truly cares. I’ve had very few negative experiences, and when I have had them I’ve said “hey that’s not cool”, and the company has fixed it as much as it could be fixed. The fact that I may be fired at some point does not invalidate that.
To me, loyalty between a company and an individual is not about the contract of work, it is about the environment that exists while you are working. Both I and the company have the option at any time to terminate the employment, that’s just part of the deal. That does not mean long term loyalty and expectations can’t exist.
As in: most often than not, in more situations than not, they have most if not all of the leverage.
I think that in this case when people say 'loyalty' they mean 'commitment over time'. "We'll dump you as soon as that option becomes slightly better than keeping you" is what people are reacting to.
It's different than being fired because of something you did/didn't do - it's the fear that something's going to change and this important part of your life (your source of income, of identity, of your professional status and one basis for your professional network, etc) will be yanked away without any real concern for the even short-term impacts on you.