I think it's more nuanced than that. If you hang out with them outside of work on a regular basis, then maybe they are genuine friends and that's great. The pro

I think it's more nuanced than that. If you hang out with them outside of work on a regular basis, then maybe they are genuine friends and that's great. The problem discussed is a different situation: You get along great with your colleagues, however you never spend time with them outside of work. Then let's say that getting along well with them nudges you to stay at the company longer even though your company/position is not a good fit for you and you should be looking for better career opportunities. You finally decide to leave the company 2 years later, then you realize that these colleagues weren't really friends after all and you should have started looking for better opportunities way earlier.