This is “meta” as in Most Effective Tactic Available, as opposed to the normal use of the word “meta” (“referring to itself or to the conventions of its genre; self-referential.”)
I don't know about this acronym... "meta" from the article is certainly not using it. The acronym definition breaks down because technically something can be meta and not be the most effective tactic available. Eg. when the rules of a game are too complex to solve in a short time, you will see players rally around a "meta" strategy until a more optimal one is discovered and vetted.
I think the author lack the context of META being the acronym for "most effective tactics available", as most of the gaming world is using it.
But the former is the latter because the most effective tactic available depends on what all of the other player in the game are going to do. The most effective tactic available is only the most effective given that other players are also going to choose the most effective tactic available.
thank you for this! I was reading the article with the latter meaning in mind, and got quite confused. Should read the comments on HN first!