Etiquette is the forms or manners established as acceptable or required by society or a profession. That's the dictionary definition. In reality, people show business etiquette when they make others feel comfortable and eliminate barriers that hinder business.
Nobody likes to be thrust into a new situation where they don't know what to do or how to act. It's very uncomfortable. The only thing that makes it worse is to have someone there who's aware of your discomfort, and belittles you for your ignorance. Not only is it embarrassing, it's just bad manners.
In this day of casual attitudes and relaxed standards, do nice manners still count in business? Absolutely. For just as saying "Please" and "Thank You" made your parents proud of you as a child, so, too, will nice manners win you friends in business. Want to put yourself far ahead of your competition? Look good AND act nicely. People will certainly take note.