The concept of "best practice" is a professional term referring to procedures that are accepted or prescribed as being correct or most effective. Best practices tend to be quite specific and focused on a concrete deliverable objective. For example, in my discipline (architecture, if I can survive school), an example of a best practice would be:
During the Design Development phase, review and confirm with the Owner the project performance requirements of the project. This avoids miscommunication and misaligned expectations that can lead to problems later on.
But I'm not sure that translates well to running a D&D game where there usually is no objective beyond having fun...
Sure, we might say in principle that talking in advance about each player's expectations for the game and having a session zero is good, but (a) that is not nearly as specific as a typical best practice example (it's more of a loose principle rather than a specific technique/practice), therefor each group using a "session zero" it's likely their "session zero" will look differently, and (b) for some group types – players who've known each other a long time, one-shots, convention games, West Marches style games – that principle might not even apply.
I wonder if there might be a disconnect resulting from unarticulated assumptions. For example, if we assume that we're cataloguing best practices for home campaigns that are not between long-time friends, are not one-shots, are not convention games, and are not West Marches style, then yeah with those assumptions in place, the above might be called a "best practice." But we've had to go through a lot of acrobatics to get there.