I believe the general idea is to allow choice in others. You don't have to agree with them, as that is your choice, but you should at least entertain their choice: hear them. Many things in our history were considered negative at first and were later adopted as the norm. I agree that venting is necessary, but understanding why you are venting is more important. Fears, interest, boredom, love. Those emotions drive us all, but few understand how they make us think.

There is no downside to your behavior in forming an opinion of another being. If someone is depressed, they have unresolved issues. If they choose this for themselves, well, that's their choice. If you perceive you can help them, it makes more sense you work on getting to the unresolved issues instead of telling them to do something they already know they shouldn't do - sleep 23 hours a day. Whether you want to dig into someone's nasty problems is up to you and your level of interest in the subject.

Yes, confusion frequently leads to blaming. I wasn't trying to indicate I was being blamed, and only used it as an example to prove a larger point: slowing or stopping your thinking opens you up to observation. Listening is a powerful thing.