Not sure if the “dabbling in armchair therapy” comment was directed at me. I think the approach of @Midwest67 (“interesting . . . you may be right”) is fine for the situation when you don’t want to engage with the person. I’m advocating the “empathy” approach when you do want to engage and the situation is not a calm discussion of pros and cons but rather an emotional one that runs the spectrum from venting to meltdown.
Empathy doesn’t mean agreeing with irrational or false statements. (Classic example is when your kid screams: “you hate me and wish I’d never been born.”) My point is that when someone is venting, the first order of business should be to acknowledge the person’s emotion, whether it’s frustration or anger or whatever. (Yes that’s so frustrating/it must be difficult to have such a demanding boss/whatever.) @doschicos gave some excellent examples: “that must be difficult” or “I wish you didn’t have to go through this.” Then and only then consider asking if they want some advice. When you jump right into advice, it can come off as though you’re saying: “You’re looking at this all wrong.” or “you did something wrong or you wouldn’t be in this situation.” Which may be true but not helpful.