Dude, sometimes people are in a financial stretch and the increase in compensation is the only reason to search for alternatives.
Especially in big corps there can be a policy of being stingy with the wages unless there is some scenario like a need for counteroffer for a high performing individual contributor.
Now, you can think the company is cheap and does not really earn you contribution.
However, the psychological reality is that people don't work in their companies - they work inside teams within companies, and the duties and the culture of the team can be great even if the company policy (likely sculpted out of feeling of ficudiary duty towards stockholders among other things) feels cheap.
Great teams and great managers are far more important for a great job than "great companies". Yes, the latent company culture affects team as well, but that's only one aspect of the whole.