[dogma1138]

I've encountered an environment where they used something similar it was ridiculous.

It turns passive aggressiveness to 11, there will always be rude people or people with poor conversations skills.

However they are usually toned down because there is a limit to how much you can interrupt someone before people tell you off, especially if there is a line manager or a supervisor present.

Now you get stuck with some douche constantly using the disagree sign to your face, and worse it can be maintained throughout your entire speech forcing you to yield or tell them to sod off which means you lose.

It also doesn't really help new or shy team members if they don't want to express an opinion they won't regardless if it's verbal or smoke signals.

Improving meetings can easily be done by having a meeting captain and a clear agenda.