Read what I quoted and then what I replied.
Knowledge of the game is no longer important in writing the program.
First, DeepMind is closed-source, so unlike Stockfish, for example, you don't know anything about how it is programmed beyond what Google engineers tell you. Second, of course it is. The computer needed to be told (in mathematical terms) what the King is; what the rules of the game are. If it was not told this then it wouldn't have any basis by which to teach itself how to be better. It first needed a human to explain what the game is in mathematical terms even if that guidance was as simple as a binary value: 1= win, 0= loss/draw
How Google chose to program that A.I. beyond those instructions is opaque to us, and what determines how it teaches itself to better understand the game on its own level. The chessmasters accelerated the sophistication of computer chess because they were able to teach the engineers/mathematicians concepts they would in turn write into the code so that the computer wasted less time on less efficient calculations. That's what separates chess software: efficiency of calculations, not volume of calculations. DeepMind is simply teaching itself how to refine its math more rapidly than the chessmasters could, but it still depended on a human to frame the game, and to frame how to more accurately predict outcomes based on accumulated data. That math itself may be predicated in part on past engines (developed with the help of chessmasters) you're blindly dismissing.
One of the most interesting observations about DeepMind has been that it often emulates classic chess strategy where all the other engines do not.
Yet, you overlooked the two main points of my post. The first point is that if you don't know how to write the program...then being able to operate the machine that does is not tantamount to understanding how to build the machine, or even how to execute the tasks the machine is capable of doing. The utility of the tasks is irrelevant to this truth, and that's why I made the second point, which was to highlight that chess never had any material utility as a skill, directly, outside of a chess match, so arguing that computers eclipsing us obviated the benefits of the hobby is to overlook the virtues of the hobby in the first place. It's a game. It was always a game. What
use will a computer make of it?
We didn't dispense with understanding arithmetic just because the calculator was invented. The abacus was obviated, not the math or its human.