When playing a cooperative game, you have to have a generally copacetic group. That has always been true, and will always be true. If you love to argue and nitpick over rules while gaming, then that's cool as long as everyone is having fun...which is consistent with this new variation of Rule Zero.
The reality is that, if things aren't working out, it isn't always as easy as "find a new group," though. Typically, gaming groups are formed from real life relationships and stuff happens in life. Nobody meshes perfectly all the time. So we can't just shop for the perfect group and are going to have to all accept some compromises. I think that's what this new framing of the rule is getting at: for the game to succeed, we all have to practice empathy and ask ourselves "is this fun for that other person, or are they just going along with it so I will shut the hell up and we can get on with the game?"
A lot of the gameplay suggestions in the rules update are basically just suggesting that we will all have a better time if we are more considerate towards each other, and if we are more up front in our communication. I think that, as DMs, we do sometimes have a tendency towards a "my way or the highway approach," and I know that I can sometimes do better at looking at things from a player perspective. I think that's all the new wording of Rule 0 is suggesting: honestly ask yourself "is this about what's fun for me, or what's fun for everyone?"
And that said, it's also imposing a responsibility to communicate what isn't fun for you. If you have some lines that you won't cross, be clear about them. I don't run "evil" campaigns; I tell my players that right at session zero. No stealing from party members in my beginner campaigns. Stuff like that.