Employers who adopt the mindset that anyone is replaceable and it would be an easy task to hire someone who has a similar or great skillset, is a dangerous mindset to be in.

When a company has a truly great employee, that employee carries value that simply cannot be replaced. They carry deep institutional knowledge of the organisation

They have extensive product, systems, and process knowledge. They have previous experience on what has worked and what hasn’t worked for the company in the past.  Great employees can influence their coworkers, which when lost, has an impact on the organisation as a whole.