The system is not as loyal to employees as it used to be, and as a result, the employees feel less need to be considerate on the way out. I haven't had an employer for over 20 years now, so take this with a grain of salt, but I feel like your main loyalty is more to your coworkers than to the corporation itself. For any company more than a few dozen employees you leaving or staying will be barely noticeable on a company-wide basis.