I would say this advice primarily applies when your competitors are solid companies working hard on the same space. Maybe less so if you have reason to believe they're deceptive and/or trouble

- Support your good competitors, not the bad ones.

- I agree on supprting competitors in an early stage market, as long there is enough beers and pizzas for everybody. In a mature market, things are different, take your time and your ressources to support...your team and your customers.